Jan 29  Wed  K.S.Williams (Carleton, Ottawa)  
16:00  Continued fractions and Eisenstein's problem  


Feb 19  Wed  M.M.Dodson (York)  
16:00  Covers, $s$lengths and order  


Feb 26  Wed  Peter Kropholler (QMW)  
16:00  Bounded cohomology  


Mar 4  Wed  David Jordan (Sheffield)  
16:00  Iterations of automorphisms and representations of rings  


Mar 18  Wed  John Greenlees (Sheffield)  
16:00  Groups and spheres  


May 6  Wed  P.Gruber (Vienna)  
16:00  Modern and classical aspects of the geometry of numbers  


May 20  Wed  E.Kappos (Sheffield)  
16:00  Dynamical systems approach to nonlinear control theory  


Jun 24  Wed  T.Lau (Alberta)  
16:00  Invariant subalgebras and subgroups of locally compact groups  


Oct 14  Wed  A.Sudbery (York)  
16:00  Quantum groups  


Oct 28  Wed  Victor Bryant (Sheffield)  
16:00  Two interesting matroid problems  


Nov 11  Wed  Richard Pinch (Cambridge)  
16:00  Pseudoprimes and Carmichael numbers  


Nov 25  Wed  C.A.McGibbon (Wayne State)  
16:00  Algebraic limits and infinite dimensional spaces  


Dec 2  Wed  Martin Holland (Sheffield)  
16:00  Differential operators, curve singularities and finite dimensional algebras  


Jan 20  Wed  K.A.Brown (Glasgow)  
16:00  What is a quantum group?  


Feb 3  Wed  B.D.Mestel (Exeter)  
16:00  An application of dynamical systems theory to adaptive control  


Feb 17  Wed  A.J.Granville (Georgia)  
16:00  Primality testing and Carmichael numbers  


Feb 24  Wed  David Benson (Oxford)  
16:00  Primality testing and Carmichael numbers  


Mar 10  Wed  M.Brodmann (Z)  
16:00  Bounds for the cohomology of projective varieties  


Mar 16  Tue  V.Lyubashenko (York)  
16:00  Algebra of functions on a quantum group at a root of unity  


May 19  Wed  Peter Dixon (Sheffield)  
16:00  Varieties of Banach algebras  


May 26  Wed  M.Herrmann (K)  
16:00  On the blowingup of powers of ideals  


May 26  Wed  N.V.Trung (Hanoi)  
16:00  Criteria for Gorenstein Rees algebras  


Oct 20  Wed  C.J.H.MacDiarmid (Oxford)  
16:00  Agedependent branching processes; recent improved estimates  


Oct 27  Wed  D.Burns (KCL)  
16:00  Adams operations, cannabalistic classes and integral representations  


Nov 17  Wed  Shaun Bullett (QMW)  
16:00  Mating quadratic maps with the modular group  


Dec 1  Wed  Bruce Westbury (Nottingham)  
16:00  State sum model invariants of 3manifolds  


Feb 2  Wed  David Mond (Warwick)  
16:00  The geometry of free divisors  


Feb 9  Wed  Ronnie Brown (Bangor)  
16:00  Holonomy, foliations and groupoids  


Feb 16  Wed  Jeremy Rickard (Bristol)  
16:00  What could be simpler than the trivial module?  


Mar 9  Wed  M.P.Brodmann (Z)  
16:00  Blowingups and their visualisation by computer  


Mar 9  Wed  T.Albu (Bucharest and Glasgow)  
16:00  Krull dimension, dual Krull dimension, and the HopkinsLevitzki theorem  


Mar 16  Wed  L.Beineke (Purdue and Oxford)  
16:00  A survey of graph decompositions  


May 4  Wed  D.Strauss (Hull)  
16:00  The semigroup $\beta\mathbb{N}$  


Jun 2  Thu  Andy Baker (Glasgow)  
16:00  Vertex operators in algebraic topology  


Jun 2  Thu  Neil Strickland (MIT)  
16:00  Isogenies and DyerLashof operations in $E_n$theory  


Oct 4  Tue  P.Polo (Pierre et Marie Curie, CNRS)  
16:00  Ktheory of twisted differential operators on complete homogeneous spaces  


Oct 5  Wed  T.Bridgeman (Liverpool)  
16:00  The marking of examination papers  


Oct 19  Wed  M.V.Karasev (Moscow)  
16:00  Noncommutative products of functions defined by ``membranes'' and ``strings''  


Oct 26  Wed  M.Hirsch (Berkeley)  
16:00  Fixed points of monotone mappings  


Nov 2  Wed  P.J.Rippon (OU)  
16:00  On the boundary of certain Siegel discs  


Nov 9  Wed  A.King (Liverpool)  
16:00  The cohomology rings of moduli spaces  


Nov 23  Wed  J.Cremona (Exeter)  
16:00  The arithmetic of elliptic curves  


Jan 11  Wed  G.R.Robinson (Leicester)  
16:00  On eigenvalues of elements of finite linear groups  


Feb 22  Wed  Karen Smith (MIT)  
16:00  Prime characteristic techniques in the study of algebraic varieties over the complex numbers  


Mar 1  Wed  Y.KosmanSchwarzbach (Paris)  
16:00  Poisson geometry and odd Poisson brackets  


Mar 8  Wed  L.Avramov (Purdue)  
16:00  Hilbert series and Laurent coefficients of graded modules  


Mar 9  Thu  L.Avramov (Purdue)  
16:00  L.c.i. homomorphisms and vanishing of AndréQuillen homology  


May 10  Wed  T.Thompson (Dalhousie)  
16:00  When are soap bubbles spheres?  an excursion into other normed spaces  


May 15  Mon  T.Bier (Ulm)  
16:00  Existence and nonexistence of magic structures  


May 17  Wed  Grant Walker (Manchester)  
16:00  Modular analogues of classical symmetric functions  


May 24  Wed  M.Cannell (George Green Memorial Fund)  
16:00  George Green, mathematician and physicist, 17931840; the background to his life and work  


May 31  Wed  I.Anderson (Glasgow)  
16:00  Remarkable revelations concerning Kirkman's schoolgirls  


Oct 4  Wed  D.Woodcock (QMW)  
16:00  The partition algebra as a `deformation' of the Schur algebra  


Oct 11  Wed  C.M.Wood (York)  
16:00  Energy in geometry  


Oct 18  Wed  R.J.Sharp (Manchester)  
16:00  Zeta functions, closed geodesics and periodic orbits of dynamical systems  


Oct 25  Wed  E.C.Lance (Leeds)  
16:00  Compact quantum groups  


Nov 1  Wed  K.M.Ball (UCL)  
16:00  The reverse isoperimetric problem  


Nov 8  Wed  Jeremy Gunawardena (HewlettPackard)  
16:00  Dynamics of nonexpansive maps  


Nov 15  Wed  John Greenlees (Sheffield)  
16:00  Algebraic shadows of equivariant topology  


Nov 29  Wed  H.Petzl (Utrecht)  
16:00  Cousin complexes and flat ring extensions  


Dec 6  Wed  Bill CrawleyBoevey (Leeds)  
16:00  General representations of quivers  


Jan 31  Wed  K.Mischaikow (Georgia Institute of Technology)  
16:00  Chaotic dynamics and the Conley index  


Feb 13  Tue  M.Brodmann (Z)  
16:00  A survey of local cohomology and connectivity in algebraic varieties  


Feb 21  Wed  E.J.Beggs (Swansea)  
16:00  Soliton interactions in the principal chiral model  


Feb 28  Wed  K.Erdmann (Oxford)  
16:00  Representations of general linear groups and symmetric groups  


Mar 4  Mon  C.Le Merdy (FranceComte)  
16:00  Operator algebra structures on commutative and noncommutative $\ell^p$  


Apr 24  Wed  Reg Wood (Manchester)  
16:00  Differential operators and the Steenrod algebra  


May 8  Wed  D.Salomon (Warwick)  
16:00  Floer homology and the general Arnold conjecture  


May 15  Wed  S.M.Rees (Liverpool)  
16:00  Some new examples of convergence groups  


May 22  Wed  T.Bier (Sheffield)  
16:00  Permutations and posets  


Aug 21  Wed  M.Filali (Oulu)  
16:00  On the semigroup $\beta$S and some applications  


Oct 9  Wed  Victor Flynn (Liverpool)  
16:00  Rational points on curves  


Oct 23  Wed  J.Roberts (Edinburgh)  
16:00  Moduli spaces of flow graphs and 3manifold invariants  


Oct 30  Wed  David Mond (Warwick)  
16:00  Families of free divisors  


Nov 12  Tue  Y.V.Selivanov (Moscow)  
16:00  Biprojective topological algebras  


Nov 20  Wed  Ronnie Brown (Bangor)  
16:00  A nonabelian tensor product of groups  


Nov 27  Wed  J.C.McConnell (Leeds)  
16:00  Effective calculation  first steps in Gröbner bases  


Dec 11  Wed  A.K.Austin (Sheffield)  
16:00  Mathematical proof  what shall we tell the students?  


Jan 29  Wed  A.S.Dzhumadil'daev (AlmaAta)  
16:00  Lie algebroids, cohomologies and noncommutative Lie algebras  


Feb 26  Wed  R.Marsh (Glasgow)  
16:00  Quantum groups and canonical bases  


Mar 5  Wed  Roger Webster (Sheffield)  
16:00  Logconvex solutions to $f(x+1)=g(x)f(x)$  $;amma$type functions  


Apr 16  Wed  V.Goryunov (Liverpool)  
16:00  Plane curves and Legendrian knots  


Apr 23  Wed  J.F.McKee (Edinburgh)  
16:00  Factoring on a desert island  


May 7  Wed  F.Vivaldi (QMW)  
16:00  Discrete dynamics and algebraic numbers  


May 7  Wed  P.Shiu (Loughborough)  
16:00  A remarkable function from Diophantine Approximations (the devil's staircase and an angel's ladder)  


May 14  Wed  A.West (Leeds)  
16:00  Surfaces which do not intersect their focal set  


May 21  Wed  Jon Carlson (Athens)  
16:00  Computers, polynomial rings and group cohomology  


Jun 2  Mon  Peter May (Chicago)  
16:00  Equivariant topology and nonequivariant applications  


Oct 21  Wed  John Hunton (Leicester)  
16:00  Quasiperiodic tilings and homotopy theory  


Oct 28  Wed  A.J.Power (Edinburgh)  
16:00  Higher dimensional categories  


Nov 11  Wed  I.Gordon (Edinburgh)  
16:00  Representations of quantum groups at roots of unity  


Nov 25  Wed  Kevin Buzzard (Imperial)  
16:00  Artin's conjecture on Lfunctions  


Dec 2  Wed  Niall Mackay (Sheffield)  
16:00  Yangians and Dorey's rule  


Dec 9  Wed  W.W.Wheeler (Leicester)  
16:00  Infinite dimensional modules for finite groups  


Jan 20  Wed  Kirill Mackenzie (Sheffield)  
16:00  Notions of double  


Feb 3  Wed  S.Merkulov (Glasgow)  
16:00  Strong homotopy and GerstenhaberBatalinVilkovoski algebras of a Kähler manifold  


Feb 17  Wed  M.Weber (Dresden)  
16:00  On finite elements in vector lattices  


Mar 3  Wed  P.Shiu (Loughborough)  
16:00  Problems on sums of two squares  


Mar 10  Wed  G.A.Jones (Southampton)  
16:00  Dessins d'enfant: geometric actions of Galois groups  


Apr 28  Wed  J.C.Robson (Leeds)  
16:00  Dedekindlike noncommutative rings  


May 12  Wed  I.R.Porteous (Liverpool)  
16:00  Robust features of surfaces in $\mathbb{R}^3$  


May 19  Wed  Burt Totaro (Cambridge)  
16:00  Singular algebraic varieties and elliptic cohomology  


May 26  Wed  K.A.Brown (Glasgow)  
16:00  Some current themes in representation theory  


Oct 13  Wed  Michael Weiss (Aberdeen)  
16:00  Homotopy theoretic analysis of spaces of smooth embeddings  


Oct 20  Wed  R.Green (Lancaster)  
16:00  Quantum algebras at $v=\infty$  


Nov 3  Wed  Srikanth Iyengar (Sheffield)  
16:00  Intersection theorems in commutative algebra  


Nov 17  Wed  A.Borovik (UMIST)  
16:00  Probabilistic recognition of black box groups  


Nov 24  Wed  John Pym (Sheffield)  
16:00  The Ellis semigroup of the action of a connected semisimple Lie group on a maximal compact subgroup  


Dec 8  Wed  Ulrike Tillmann (Oxford)  
16:00  Moduli spaces of Riemann surfaces and CFT  


Dec 15  Wed  H.Hauer (Nottingham)  
16:00  Generalised RiemannRoch formulas  


Feb 9  Wed  Susan Howson (Nottingham)  
16:00  NonAbelian Iwasawa theory and applications to elliptic curves  


Feb 16  Wed  M.Brodmann (Z)  
16:00  Associated primes of local cohomology modules  


Feb 18  Fri  Larry Smith (G)  
16:00  Coinvariants, Jacobians and Poincaré duality  


Mar 1  Wed  Ronnie Brown (Bangor)  
16:00  Nonabelian methods for computing modules of identities among relations for presentations of groups: crossed complexes  


Mar 15  Wed  A.Henke (Kassel)  
16:00  The Sierprinski gasket, representations and the symmetric group  


Mar 22  Wed  Ian Grojnowski (Cambridge)  
16:00  Rigid structure and the symmetric group  


Apr 5  Wed  Y.KosmannSchwarzbach (Ecole Polytechnique)  
16:00  Poisson homogeneous spaces  


May 3  Wed  Moty Katzman (Sheffield)  
16:00  Edge algebras which are complete intersections  


May 10  Wed  Ran Levi (Aberdeen)  
16:00  The spaces of equivalences between $p$completed classifying spaces  


May 22  Mon  K.Mischaikow (Georgia Institute of Technology)  
16:00  Rigorous computation of lowdimensional dynamics and the combinatorial geometry of flows  


Sep 27  Wed  A.Frankild (Copenhagen)  
16:00  Vanishing of local homology and some applications  


Oct 2  Mon  J.Br (Stuttgart)  
16:00  Almost periodic sequences. binary additive problems and the circle method  


Oct 11  Wed  Roger Plymen (Manchester)  
16:00  The BaumConnes conjecture and the local Langlands conjecture for GL(n): are they related?  


Oct 17  Tue  P.Jorgensen (Copenhagen)  
16:00  Spectra of modules  


Oct 18  Wed  P.CoveyCrump (GCHQ)  
16:00  Campanology and mathematics  


Nov 1  Wed  H.Khudaverdyan (visiting UMIST)  
16:00  BatalinVilkovisky formalism geometry and semidensities of odd symplectic manifolds  


Nov 15  Wed  Hellen Colman (Sheffield)  
16:00  LScategory of compact Hausdorff foliations  


Nov 22  Wed  S.Hurder (Chicago)  
16:00  Foliations: at the crossroads of geometry and topology  


Nov 22  Wed  Imre Leader (Cambridge)  
16:00  Set systems with few disjoint pairs  


Nov 29  Wed  J.Cremona (Nottingham)  
16:00  Reduction of binary formshow to find small equations for hyperelliptic curves  


Dec 6  Wed  David Jordan (Sheffield)  
16:00  Rings generated by Eulerian derivatives  


Dec 13  Wed  A.Wilkie (Oxford)  
16:00  Tame topology and Ominimal structures  


Feb 7  Wed  S.Koenig (Leicester)  
16:00  SchurWeyl duality and dominant dimension  


Feb 14  Wed  Vladimir Bavula (Sheffield)  
16:00  Holonomic Dmodules, the Dixmier problem and the Jacobian conjecture  


Feb 28  Wed  A.Volovikov (Steklov, visiting Liverpool)  
16:00  Indexes of Gspaces  


Mar 7  Wed  V.Nikulin (Liverpool)  
16:00  A theory of Lorenzian (or hyperbolic) KacMoody algebras  


Mar 13  Tue  Matthew Ando (Urbana)  
16:00  Equivariant elliptic cohomology of spin bundles  


Mar 14  Wed  Alan Camina (UEA)  
16:00  Sizes of conjugacy classes  what do they tell us about the structure of finite groups?  


Mar 20  Tue  W.Timmermann (Dresden)  
16:00  Mathematical structures in quantum physics  some historical remarks  


Mar 21  Wed  B.Zilber (Oxford)  
16:00  Logic and Schanueltype conjectures  


Mar 28  Wed  S.Galbraith (Bristol)  
16:00  Abelian varieties and cryptography  


Apr 4  Wed  Andrew Pressley (KCL)  
16:00  Representations of quantum affine algebras  


May 2  Wed  Charles Thomas (Cambridge)  
16:00  Geometric structures on fake projective and lens spaces  


May 9  Wed  John Greenlees (Sheffield)  
16:00  Old and new dualities in algebra and topology  


May 16  Wed  Marian Anton (Sheffield)  
16:00  Undetected general linear group cohomology  


May 17  Thu  H.B.Foxby (Copenhagen)  
16:00  Properties of homomorphisms in commutative algebra  


Oct 3  Wed  S.Donkin (QMW)  
16:00  Some remarks on cohomology of line bundles on flag varieties  


Oct 10  Wed  B.Koeck (Southampton)  
16:00  Computing the homology of Koszul and DoldPuppe complexes  


Oct 17  Wed  M.Mackaay (Nottingham)  
16:00  Categorical groups in differential geometry and 4dimensional geometry  


Oct 24  Wed  Ieke Moerdijk (Utrecht)  
16:00  Models for the leaf spaces of a foliation  


Nov 7  Wed  G.Robinson (Birmingham)  
16:00  Local structure and blocks  


Nov 13  Tue  M.Brodmann (Z)  
16:00  Bounding sheaf cohomology by the diagonal  


Nov 14  Wed  J.Keating (Bristol)  
16:00  Random matrix theory and $\zeta(1/2+it)$  


Nov 20  Tue  R.Hill (UCL)  
16:00  The Kubota symbol on $SL_n$  


Nov 26  Mon  K.Mischaikow (Georgia Institute of Technology)  
16:00  Searching for holes and volumes: biomedical imaging and computational topology  


Dec 5  Wed  Frank Neumann (Leicester)  
16:00  Etale homotopy and moduli of stacks  


Dec 12  Wed  Imma Galvez (Sheffield)  
16:00  Elliptic genera and invariants of manifolds with boundary  


Dec 19  Wed  Rachel Camina (Cambridge)  
16:00  Linearity of propgroups  


Feb 12  Tue  Angus MacIntyre (University of Edinburgh)  
16:00  Connections between Schanuel's Conjecture and Logic.  


Feb 13  Wed  M.Gross (Warwick)  
16:00  Topological mirror symmetry  


Feb 19  Tue  Johannes Kellendonk (University of Cardiff)  
16:00  Topological aspects of aperiodic ordered systems.  


Feb 20  Wed  Alan Camina (Sheffield)  
16:00  Pro$p$groups of finite width  


Feb 26  Tue  Aidan Schofield (University of Bristol)  
16:00  Noncommutative moduli spaces of vector bundles  


Feb 27  Wed  Ian Stewart (Leicester)  
16:00  Finite model theory, complexity theory and program schemes (The MathFIT initiative)  


Mar 5  Tue  Tom Lenagan (University of Edinburgh)  
16:00  Noncommutative Dehomogenisation  


Mar 6  Wed  C.Cocks (GCHQ)  
16:00  Recent developments in identifierbased public key cryptosystems  


Mar 13  Wed  Greg Sankaran (Bath)  
16:00  Nef divisors in the moduli of abelian varieties  


Mar 19  Tue  Arthur Chatters (University of Bristol)  
16:00  Generalised quaternions  


Mar 26  Tue  John McCleary (Vassar (Cambridge))  
16:00  Hochschild homology and closed geodesics  


Apr 2  Tue  Kevin Houston (University of Leeds)  
16:00  Images of Maps  


Apr 9  Tue  Sarah Whitehouse (Sheffield)  
16:00  Hopf algebras related to Ktheory.  


Apr 17  Wed  Mike Prest (Manchester)  
16:00  GabrielZariski spectra of module categories  


Apr 24  Wed  Hugh Morton (Liverpool)  
16:00  Algebras constructed from knot theory  


May 7  Tue  Elizabeth Winstanley (Sheffield, Applied Mathematics)  
16:00  1905 and all that: general relativity for algebraists  


May 8  Wed  A.Veselov ( Loughborough)  
16:00  Algebra and geometry of quantum CalogeroMoser problems  


May 14  Tue  George Wilson (Imperial College)  
16:00  Differential operators on algebraic varieties  


May 15  Wed  L.O'Carroll ( Edinburgh)  
16:00  Maximal CohenMacaulay modules over hypersurfaces: some algebra, some geometry, some history+D213  


May 21  Tue  Simon Willerton (Sheffield)  
16:00  Connections on gerbes  


May 22  Wed  N.Yui (Queen's)  
16:00  Mirror moonshine phenomena  


Sep 25  Wed  Mr A Middleditch (Sheffield)  Applied Mathematics Colloquium  
Measuring ocean surface currents using HF radar  


Oct 2  Wed  Prof Ronald Smith (Loughborough)  Applied Mathematics Colloquium  
The optimal compact finitedifference scheme for the diffusion equation with flow  


Oct 2  Wed  T.Ward (UEA)  
16:00  Commuting maps and commutative algebra  


Oct 9  Wed  Dr Makis Kappos (Sheffield)  Applied Mathematics Colloquium  
Singularities, Far and Near  


Oct 9  Wed  Ian Leary (Southampton)  
16:00  An introduction to $L^2$ homology  


Oct 16  Wed  Lars Hesselholt (MIT)  
16:00  Algebraic Ktheory and trace invariants  


Oct 23  Wed  Dr I. Ballai (Sheffield)  Applied Mathematics Colloquium  
Coronal Seismology  


Oct 23  Wed  Brooke Shipley (Purdue)  
16:00  Rings up to homotopy  


Oct 30  Wed  Dr D. Roscoe (Sheffield)  Applied Mathematics Colloquium  
Is dark matter the new phlogiston?  


Nov 6  Wed  Dr Bill Lionheart (UMIST)  Applied Mathematics Colloquium  
Anisotropic inverse boundary value problems in electromagnetics  


Nov 13  Wed  Rick Jardine (Western Ontario)  
16:00  Presheaves of chain complexes  


Nov 20  Wed  Dr V. Yudovich (Hull)  Applied Mathematics Colloquium  
Cosymmetry and its application in mechanics  


Nov 20  Wed  A.Zalesski (UEA)  
16:00  Hurwitz groups  


Nov 27  Wed  Mr T. Antypas (Athens)  Applied Mathematics Colloquium  
The description of concentration time series of instantaneously released gases in the atmosphere via the proper orthogonal decomposition  


Nov 27  Wed  Jan Schroer (Leeds)  
16:00  On the BerensteinZelevinsky conjecture  


Dec 4  Wed  Prof A. Hood (St. Andrews)  Applied Mathematics Colloquium  
Phase mixing: heating mechanism for coronal holes  


Dec 4  Wed  ChoHo Chu (QMW)  
16:00  Harmonic functions and random walks on groups  


Dec 11  Wed  Prof Sir J. Kingman (Isaac Newton Institute)  Applied Mathematics Colloquium  
On teaching Poisson processes  


Dec 11  Wed  P.Giblin (Liverpool)  
16:00  Features of Surfaces  


Dec 18  Wed  Frazer Jarvis (Sheffield)  
16:00  The Fermat equation over real quadratic fields  


Jan 9  Thu  Ieke Moerdijk (Utrecht)  
16:00  Lie groupoids, gerbes and nonabelian cohomology  


Feb 5  Wed  Dr Kristof Petrovay (Eotvos University, Budapest)  Applied Mathematics Colloquium  
Secondary shear instability in the solar tachocline  


Feb 12  Wed  Dr Stephen Belcher (Reading, Meteorology)  Applied Mathematics Colloquium  
The role of surface waves in dynamics of the ocean mixed layer  


Feb 19  Wed  Prof Ray Atkin (Sheffield)  Applied Mathematics Colloquium  
Inaugural lecture: Fluids with a future?  


Feb 21  Fri  Dr Ingo MuellerWodarg (UCL, Atmospheric Physics Laboratory)  Applied Mathematics Colloquium  
The application of General Circulation Models to terrestrial and planetary upper atmospheres  


Feb 26  Wed  Prof Vladimir Vladimirov (Hull)  Applied Mathematics Colloquium  
Virial equation in fluid dynamics  


Mar 5  Wed  Dr Christos Vassilicos (Imperial College London, Aeronautics)  Applied Mathematics Colloquium  
Turbulent diffusion  


Mar 19  Wed  Prof Alan Zinober (Sheffield)  Applied Mathematics Colloquium  
From the brachistochrone to the calculus of variations and modern control theory  


Mar 26  Wed  Prof John Gibbon (Imperial College London)  Applied Mathematics Colloquium  
Infinite energy singularity formation in a class of solutions of the 3D Euler equations  


Apr 2  Wed  Prof Farideh Honary (Lancaster)  Applied Mathematics Colloquium  
Modern Riometry: techniques and results  


May 6  Tue  Prof Xia (China)  Applied Mathematics Colloquium  
Periodic orbits arising from deltamodulated feedback control  


May 7  Wed  Prof Shadia Habbal (Aberystwyth, Physics)  Applied Mathematics Colloquium  
The solar wind and the hidden secrets of the Sun  


May 14  Wed  Dr Eleri Pryse (Aberystwyth, Physics)  Applied Mathematics Colloquium  
Imaging nearEarth space  


May 29  Thu  Dr Louise Harra (UCL, MSSL)  Applied Mathematics Colloquium  
Solar flare and Coronal Mass Ejections  


Oct 1  Wed  Dr R. Balthazor (Sheffield)  Applied Mathematics Colloquium  
Modelling the Upper Atmosphere  a historical perspective  


Oct 1  Wed  Charudatta Hajarnavis (University of Warwick)  
16:00  A symmetry theorem for invertible ideals and its applications.  


Oct 8  Wed  Dr N. Mole (Sheffield)  Applied Mathematics Colloquium  
Surface waves in random media: applications to solar physics  


Oct 22  Wed  Dr Kristof Petrovay (Eotvos University, Budapest)  Applied Mathematics Colloquium  
The decay of sunspots as a nonlinear turbulent erosion process  


Oct 22  Wed  Paul Turner (HeriotWatt)  
16:00  Putting the fields back into Topological Quantum Field Theory  


Oct 29  Wed  Prof David Hughes (Leeds)  Applied Mathematics Colloquium  
Large and smallscale dynamo action  


Oct 29  Wed  Peter Rowlinson (Stirling)  
16:00  Star complements in finite graphs  


Nov 5  Wed  Dr Mervyn Freeman (British Antarctic Survey)  Applied Mathematics Colloquium  
Multiscale SunEarth connections  


Nov 5  Wed  Richard Thomas (Imperial)  
16:00  Symmetry groups and geometrics PDEs  


Nov 12  Wed  Dr John Brooke (CSAR, Manchester)  Applied Mathematics Colloquium  
Using Carrington's Legacy: analysing the spatiotemporal structure of the solar cycle from 1853 to 2003  


Nov 19  Wed  Dr Alan Aylward (UCL, Physics and Astronomy)  Applied Mathematics Colloquium  
Solar variability and climate change: what CMAT model can tell us about the possible mechanisms  


Nov 19  Wed  Tom Bridgeland (Edinburgh)  
16:00  Moduli spaces and birational geometry  


Nov 26  Wed  Dr William Wilkinson (CMIS, Brighton)  Applied Mathematics Colloquium  
The Earth's quasiparallel bow shock: review of observations and outstanding questions  


Nov 26  Wed  James McKee (Royal Holloway, University of London)  
16:00  Salem numbers via interlacing  


Dec 10  Wed  Prof Joe Buckley (Royal Military College of Canada, Physics)  Applied Mathematics Colloquium  
Ocean waves and microwaves  


Dec 10  Wed  Peter Kropholler (Glasgow)  
16:00  Classifying Spaces for Proper Group Actions  


Dec 17  Wed  Dr Michael Warby (Brunel)  Applied Mathematics Colloquium  
The computational modelling of the constrained inflation of solid polymers in the context of thermoforming  


Dec 17  Wed  Iain Gordon (Glasgow)  
16:00  Symplectic reflection algebras.  


Feb 11  Wed  Shahn Majid (Queen Mary, University of London)  
16:00  Quantization of differential structures and quasiassociative geometry  


Feb 18  Wed  Kohji Yanagawa (University of Osaka, Japan)  
16:00  Stanley Reisner rings, Sheaves and PoincareVerdier Duality  


Mar 3  Wed  Roger HeathBrown (Oxford)  
16:00  Geometric problems in analytic number theory  


Mar 10  Wed  Dr Itsuki Handoh (Sheffield)  Applied Mathematics Colloquium  
The midCretaceous biogeochemical cycles and climate change  


Mar 10  Wed  Colin Ingalls (Warwick)  
16:00  Noncommutative Surfaces and Birational Geometry  


Mar 17  Wed  Theodore Voronov (UMIST)  
16:00  Higher derived brackets and homotopy algebras  


Mar 24  Wed  Dr Elizabeth Lucek (ICSTM)  Applied Mathematics Colloquium  
Cluster observations of the Earth's bow shock  


Mar 24  Wed  Shaun Bullett (Queen Mary, University of London)  
16:00  Dynamics of Holomorphic Correspondences  


Mar 31  Wed  Dr John Porrill (Sheffield, Psychology)  Applied Mathematics Colloquium  
Why neuroscience needs mathematicians?  


Mar 31  Wed  Gavin Brown (University of Warwick)  
16:00  Classification in algebraic geometry.  


Apr 28  Wed  Dr David Tsiklauri (Salford, Computer Science and Engineering)  Applied Mathematics Colloquium  
Interaction of Alfven waves with plasma structures  


Apr 28  Wed  Elizabeth Winstaley (University of Sheffield)  
16:00  To Infinity and Beyond: Local and Global Geometry in General Relativity  


May 5  Wed  Prof Slava Kurylev (Loughborough)  Applied Mathematics Colloquium  
Uniqueness and stability in multidimensional inverse problems  


May 5  Wed  Kirill Mackenzie (University of Sheffield)  
16:00  Duality for double and multiple structures  


May 12  Wed  Dr David Roscoe (Sheffield)  Applied Mathematics Colloquium  
Discrete dynamical states in galactic discs: New insights, new data  


May 12  Wed  Marcus du Satoy (Oxford)  
16:00  Through the looking glass: groups from a number theoretic perspective  


May 17  Mon  Vic Snaith (Southampton)  
16:00  StiefelWhitney classes and symplectic local root numbers  


May 19  Wed  Prof Viktor Shrira (Keele)  Applied Mathematics Colloquium  
Quasimodes in shear flows: a working concept  


May 25  Tue  Reinhold H (SAP)  
16:00  Evolutions, derivations and differential forms  


May 26  Wed  Tony Sudbery (University of York)  
16:00  Quantum Information Theory: a confection of mathematics, physics and computer science  


May 28  Fri  Linus Kramer (Darmstadt)  
16:00  Buildings and Symmetric Spaces: Perspectives and Horizons  


Jun 29  Tue  Stefan Bauer (Bielefeld)  
16:00  Monopoles and Mergers in four Dimensions  


Sep 1  Wed  Dr M. Miesch (HAO/NCAR, Boulder (USA))  Applied Mathematics Colloquium  
Behind the HYPE: A ThinShell Model for the Solar Tachocline  


Sep 17  Fri  Dr Hien Vo (Aberystwyth)  Applied Mathematics Colloquium  
Various aspects of the plasmasphere using satellite and ground data along with a study of the selforganizing criticality in using global auroral images  


Sep 29  Wed  Dr E. Benilov (Limerick)  Applied Mathematics Colloquium  
Explosive instability in linear systems with stable eigenmodes  


Sep 29  Wed  Neil Dummigan (Sheffield)  
16:00  Elliptic Curves and Modular Degrees  


Sep 29  Wed  Neil Dummigan (Sheffield)  Pure Maths Colloquium  
16:00  Elliptic Curves and Modular Degrees  
Hicks Seminar Room J11  


Oct 6  Wed  Dr R. Kerr (Warwick)  Applied Mathematics Colloquium  
Structure functions as a tool for atmospheric analysis  


Oct 6  Wed  Ben Green (Cambridge)  Pure Maths Colloquium  
16:00  Arithmetic progressions of primes  
Hicks Seminar Room J11  
Abstract: I will discuss some aspects of the recent proof that there are arbitrarily long arithmetic progressions of primes, which is joint work with Terry Tao. I will also discuss some more recent work of ours, which gives an asymptotic for the number of 4term APs of primes, all less than N. 



Oct 13  Wed  Dr W. Chaplin (Birmingham, Physics and Astronomy)  Applied Mathematics Colloquium  
Sounding the deep solar interior: modern challenges for global Helioseismology  


Oct 14  Thu  Bernhard Hanke (Munich)  Pure Maths Colloquium  
14:00  Enlargeability and index theory  
Hicks Seminar Room J11  


Oct 20  Wed  Dr A. FerrizMas (Vigo, Spain)  Applied Mathematics Colloquium  
Fluid mechanical aspects in solar magnetism: How can magnetic fields of 100 kG be produced?  


Oct 20  Wed  Burt Totaro (Cambridge)  Pure Maths Colloquium  
16:00  Topological Invariants of Singular Varieties  
Hicks Seminar Room J11  
Abstract: We start with some examples of singularities that algebraic varieties can have in low dimensions. We look at resolutions of singularities, that is, mappings from a smooth manifold onto a singular space. One can try to define invariants of a singular space using known invariants of its resolution. I will describe some successful invariants of this type: intersection homology theory, the elliptic genus, and stringy Betti numbers. 



Oct 27  Wed  Prof I. Moss (Newcastle)  Applied Mathematics Colloquium  
Warm inflation and the hot big bang  


Oct 27  Wed  Jan Schroer (Leeds)  Pure Maths Colloquium  
16:00  Universal Bases for KacMoody Lie Algebras  
Hicks Seminar Room J11  
Abstract: The talk aims to explain the connection between the following topics:  Canonical Bases for KacMoody Lie Algebras  Representation Theory of Preprojective Algebras  Varieties of Modules. 



Nov 3  Wed  Prof G. Tallents (York, Physics)  Applied Mathematics Colloquium  
The opacity of hot dense plasmas: application to laboratory and solar examples  


Nov 3  Wed  Roger Plymen (Manchester)  Pure Maths Colloquium  
16:00  Twobytwo matrices from two points of view  
Hicks Seminar Room J11  
Abstract: This will mainly be about SL(2,C) and SL(2,R). The first point of view is that of HarishChandra, and leads to irreducible unitary representations, the Plancherel measure and the tempered dual. The second point of view is that of Connes and Kasparov, which leads from the reduced C*algebra back to the representations rings R(SU(2)) and R(SO(2)). I will relate these two points of view, and describe recent results for GL(3) (joint work with AnneMarie Aubert). 



Nov 10  Wed  David Calderbank (Edinburgh)  Pure Maths Colloquium  
16:00  Toric selfdual Einstein metrics  
Hicks Seminar Room J11  


Nov 11  Thu  Prof S. Quegan (Sheffield)  Applied Mathematics Colloquium  
A short walk around the Carbon cycle  


Nov 17  Wed  Peter Larcombe (Derby)  Pure Maths Colloquium  
16:00  Some Recent Results on Catalan Numbers and CatalanRelated Sequences  
Hicks Seminar Room J11  
Abstract: In this talk I will give a brief introduction to the well known Catalan number and present research results associated with them, some of which are set in historical context. Two recently announced Catalanrelated sequences which arise from elliptic integralsnamely, the so called CatalanLarcombeFrench and FennesseyLarcombeFrenchare then introduced, and their properties discussed. 



Nov 18  Thu  Dr N. Mavromatos (King's College, London)  Applied Mathematics Colloquium  
CPT violation and decoherence: is there a chance of observing something?  


Nov 24  Wed  Dr P. Browning (UMIST)  Applied Mathematics Colloquium  
Heating the solar corona by nanoflares  


Nov 24  Wed  Michael Farber (Durham)  Pure Maths Colloquium  
16:00  Topology of Robot Motion Planning  
Lecture Theatre 2, Hicks Building  
Abstract: In the talk I will show that one may predict the character of instabilities of robot's behavior knowing the cohomology algebra of its configuration space. 



Nov 26  Fri  Prof P. Diamond (UCSD)  Applied Mathematics Colloquium  
Zonal flows in Laboratory plasmas  


Dec 1  Wed  Imre Leader (Cambridge)  Pure Maths Colloquium  
16:00  Partition Regular Equations  
Hicks Seminar Room J11  


Dec 7  Tue  Alfonso GraciaSaz (UC Berkeley)  
Duality of triple structures and beyond  
Abstract: A double vector bundle is a commutative diagram $$\xymatrix{ D \ar[r] \ar[d] & B \ar[d] \\ A \ar[r] & M }$$ where every vertex is a smooth manifold, every edge is a vector bundle, plus compatibility conditions between the two structures on $D$. $D$ can be dualized with respect to these 2 structures. These 2 dualization operations have order 2, but do not commute, and generate a group isomorphic to the symmetric group $S_3$. Mackenzie found a geometric interpretation and started the study of triple vector bundles, which is not a straightforward generalization. We will show recent work on the calculation of the group generated by the $n$ dualizations of a $n$fold vector bundle, which turns out to be a central extension of $S_{n+1}$ by ${n\choose 2}  1$ copies of $C_2$. 



Dec 8  Wed  Dr E. Winstanley (Sheffield)  Applied Mathematics Colloquium  
What Hawking did: why all the fuss in Dublin?  


Dec 8  Wed  Dave Applebaum (Sheffield)  Pure Maths Colloquium  
16:00  Harmonic Analysis of Semigroups of Measures on Locally Compact Groups  
Hicks Seminar Room J11  


Dec 15  Wed  Dr C. van de Bruck (Sheffield)  Applied Mathematics Colloquium  
Cosmology and Extra Dimensions  


Dec 15  Wed  Victor Flynn (Liverpool)  Pure Maths Colloquium  
16:00  Visualisation in Higher Genus  
Hicks Seminar Room J11  


Jan 13  Thu  Larry Smith (G)  
16:00  Macaulay Duals for Hilbert Ideals of Reflection Groups  
Hicks Seminar Room J11  


Feb 1  Tue  Samuel W (Sheffield)  Topology Seminar  
16:00  Iadic towers and Koszul complexes in algebra and topology  
Hicks Seminar Room J11  


Feb 8  Tue  Samuel W (Sheffield)  Topology Seminar  
14:00  Iadic towers and Koszul complexes in algebra and topology  
Hicks Seminar Room J11  


Feb 9  Wed  Dr J. J. Healey (Keele)  Applied Mathematics Colloquium  
A strange instability with growth normal to a boundary layer  


Feb 9  Wed  Victor Snaith (Sheffield)  Pure Maths Postgraduate Seminar  
12:00  Algebraic topology at work: the nonexistence of maps of Hopf invariant one  
Hicks Seminar Room J11  


Feb 9  Wed  Peter Cameron (Queen Mary)  Pure Maths Colloquium  
16:00  The Rado graph and the Urysohn space  
Hicks Seminar Room J11  


Feb 14  Mon  Moty Katzman (Sheffield)  Algebra / Algebraic Geometry seminar  
16:10  Graphs and their ideals  
Hicks Seminar Room J11  


Feb 15  Tue  Samuel W (Sheffield)  Topology Seminar  
14:00  Iadic towers and Koszul complexes in algebra and topology  
Hicks Seminar Room J11  


Feb 16  Wed  Dr D. Roscoe (Sheffield)  Applied Mathematics Colloquium  
Reaction in classical electrodynamics  


Feb 16  Wed  Sam Marsh (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  $F_{l}$representations of finite abelian $p$groups  
Hicks Seminar Room J11  
Abstract: to appear 



Feb 16  Wed  Rob de Jeu (Durham)  Pure Maths Colloquium  
16:00  Algebraic Ktheory of number fields, regulators, zeta functions,....  
Hicks Seminar Room J11  
Abstract: We discuss relations between the Ktheory of number fields and their zeta functions, both classically and (more conjecturally) p adically. Apart from talking about the theoretical description of those regulators we also touch upon aspects on how to compute them in practice. 



Feb 21  Mon  Victor Snaith (Sheffield)  Algebra / Algebraic Geometry seminar  
16:10  Stickelberger series Part IV  
Hicks Seminar Room J11  


Feb 22  Tue  Samuel W (Sheffield)  Topology Seminar  
14:00  Iadic towers and Koszul complexes in algebra and topology  
Hicks Seminar Room J11  


Feb 23  Wed  Dave Barnes (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Rational homotopy of spheres  
Hicks Seminar Room J11  


Feb 28  Mon  Victor Snaith (Sheffield)  Algebra / Algebraic Geometry seminar  
16:10  Stickelberger V  
Hicks Seminar Room J11  
Abstract: This is the last in the Stickelberger series. In this one, finally the BIG CONJECTURE will be revealed and a sketch proof of the evidence for it will be given. 



Mar 1  Tue  Neil Strickland (Sheffield)  Topology Seminar  
14:00  Morava Ktheory I  
Hicks Seminar Room J11  
Abstract: I will give a series of three or four lectures introducing Morava Ktheory and Morava Etheory. 



Mar 2  Wed  Dr J. Kaplunov (Manchester)  Applied Mathematics Colloquium  
Explicit asymptotic models for surface elastic and electroelastic waves  


Mar 2  Wed  Nong Sasom (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Leonard triples and the quintization of U(sl2)  
Hicks Seminar Room J11  


Mar 2  Wed  Andrei Lazarev (Bristol)  Pure Maths Colloquium  
16:00  pdivisible groups associated to generalized cohomology theories of EilenbergMac Lane spaces  
Hicks Seminar Room J11  
Abstract: It is wellknown that a generalized cohomology theory applied to the infinite dimensional complex projective space $CP^\infty$ often gives rise to a onedimensional group law. This fact has innumerable applications in stable homotopy theory. One particularly important class of a one dimensional formal group is associated with $K(n)^* CP^\infty)$ where $K(n)$ is the nth Morava Ktheory. This is an essentially unique example of a onedimensional formal group of height $n$ over a field. It turns out that if one replaces $CP^n=K(Z,2)$ with $K(Z,l) $, the integral EilenbergMac Lane space with $\pi_l=Z$ then the corresponding object is a formal group of finite height (a.k.a. smooth pdivisible group). This is essentially a 25 year old result of RavenelWilson although they did not phrase it in this way. Letting l vary we obtain a collection of pdivisible groups which possesses a remarkable symmetry. Particularly, any p divisible group enters in this collection together with its Serre dual (an analogue of the notion of principal polarization for abelian schemes). This and related results are obtained by studying the Dieudonne modules associated to the corresponding p divisible groups. This is a joint work of myself with Victor Buchstaber. 



Mar 7  Mon  Holger Brenner (Sheffield)  Algebra / Algebraic Geometry seminar  
16:10  The Frobenius homomorphism  what it annihilates and how fast  
Hicks Seminar Room J11  
Abstract: Let C denote a smooth projective curve over a field of positive characteristic p. We consider a cohomology class $c \in H^1 (C,S)$ for a vector bundle S over C and ask whether c is annihilated by some power of the absolute Frobenius on C  and if so, which power annihilates it. This question is related to the computation of the Frobenius closure of an ideal in the coordinate ring over C. 



Mar 9  Wed  Dr C. Mandrini (IAFE, Argentina)  Applied Mathematics Colloquium  
Magnetic Helicity: linking solar to interplanetary phenomena  


Mar 9  Wed  Mike Holcombe (Sheffield, Computer Science)  Pure Maths Colloquium  
16:00  Algebraic techniques for Software Testing  
Hicks Seminar Room J11  
Abstract: Software testing is the most expensive and difficult part of the software production process. IBM, for example estimate that testing and reviewing activities account for at least 50% of any project, in safety critical projects it can reach 90%. The sales of software in the UK in 2001 was 



Mar 14  Mon  Manuel Blickle (Essen)  Algebra / Algebraic Geometry seminar  
16:10  Local cohomology multiplicities via etale cohomology  
Hicks Seminar Room J11  
Abstract: I will show how certain local cohomology invariants (introduced by Lyubeznik) can be completely described in terms of etale cohomology. This generalizes earlier known results, which gave a topological description of these invariants for isolated complex singularities, in two different directions. For once our techniques apply to a significantly larger class of singularities (in particular all complete intersections are inluded) and secondly (and more importantly) our results are valid in positive characteristic also. I will use this result as an excuse to explain a recent RiemannHilberttype correspondence due to Emerton Kisin which is the tool that allows us to also treat the positive characteristic case. 



Mar 15  Tue  Neil Strickland (Sheffield)  Topology Seminar  
14:00  Morava Ktheory III  
Hicks Seminar Room J11  
Abstract: I will discuss the Morava Ktheory of various spaces, such as classifying spaces of finite groups. 



Mar 16  Wed  MaryJane Strong (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  An introduction to Hopf algebras  
Hicks Seminar Room J11  


Mar 16  Wed  Nick ShepherdBarron (Cambridge)  Pure Maths Colloquium  
16:00  Geometry of tangent bundles and effective Mordell over function fields.  
Hicks Seminar Room J11  


Apr 12  Tue  Al Weiss (University of Alberta)  
14:00  tba  
Hicks Seminar Room J11  


Apr 13  Wed  Dr J. Winkler (Sheffield, Computer Science)  Applied Mathematics Colloquium  
A comparison of condition numbers of the full rank least squares problem  


Apr 13  Wed  Ian Young (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Alice, Bob and elliptic curves  
Hicks Seminar Room J11  


Apr 13  Wed  Bernhard Koeck (Southampton)  Pure Maths Colloquium  
16:00  The ChevalleyWeil formula in positive characteristic.  
Hicks Seminar Room J11  
Abstract: Let G be a finite group acting on an algebraic curve X. This action induces an action on various RiemannRoch spaces such as the vector space of global holomorphic differentials on X. We determine these (modular) representations in local terms, thereby generalizing the classical ChevalleyWeil formula from characteristic 0 to the socalled weakly ramified case, an important case of wild ramification. 



Apr 18  Mon  Andrew Stacey (Sheffield)  Topology Seminar  
14:00  The Differential Topology of Loop Spaces I  
Hicks Seminar Room J11  
Abstract: The aim of these seminars is to provide a gentle but detailed introduction to the study of loop spaces as manifolds. This is a topic which has a long history, dating back at least to the days of Morse, and which has recently received renewed interest due to its strong links with string theory. We shall end this miniseries with an overview of my work on the Dirac operator on loop spaces. This finale will dictate the itinery of the tour: 1. What is an infinite dimensional manifold and how do we know that the loop space is one? 2. What does it look like, what can we do with it, and what do we want to do with it? 3. What's the big deal about Dirac operators in infinite dimensions? It is intended that anyone with basic differential topology should be able to follow these seminars. 



Apr 20  Wed  Dr Gunnar Hornig (St. Andrews)  Applied Mathematics Colloquium  
Threedimesional magnetic reconnection  


Apr 20  Wed  Phil Martin (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  tba  
Hicks Seminar Room J11  


Apr 20  Wed  Ivan Tomasic (Lyon)  Pure Maths Colloquium  
16:00  Weil conjectureswith a difference  
Hicks Seminar Room J11  
Abstract: While the classical Weil conjectures are concerned with counting points on varieties over finite fields, we consider the problem of counting points on \emph {difference} varieties over algebraic closures of finite fields with powers of Frobenius. This context is suitable e.g. for uniform treatment of Ree and Suzuki families of finite simple groups. 



Apr 26  Tue  Andrew Stacey (Sheffield)  Topology Seminar  
15:00  The Differential Topology of Loop Spaces II  
Hicks Seminar Room J11  


Apr 27  Wed  Prof. Carlo Barenghi (Newcastle)  Applied Mathematics Colloquium  
The TaylorCouette problem: an old flow with new twists  


Apr 27  Wed  Vicky Hinchcliffe (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  GelfandKirillov dimension  
Hicks Seminar Room J11  


Apr 27  Wed  Nick Bingham (Sheffield, Probability and Statistics)  Pure Maths Colloquium  
16:00  Mercerian theorems  
Hicks Seminar Room J11  


May 3  Tue  Andrew Stacey (Sheffield)  Topology Seminar  
15:00  The Differential Topology of Loop Spaces III  
Hicks Seminar Room J11  


May 4  Wed  Dr Erwin Verwichte (Warwick)  Applied Mathematics Colloquium  
Transverse waves in the solar corona  


May 4  Wed  Alan Lauder (Oxford)  Pure Maths Colloquium  
16:00  Title: Effective methods in rigid cohomology  
Hicks Seminar Room J11  
Abstract: Given a system of polynomial equations over a finite field, one may associate with it a finite dimensional vector space, known as the ``rigid cohomology'' of the system. This construction is very useful; for example, it allows one to prove good bounds on the number of solutions to the system over the finite field (Weil conjectures). The construction was first proposed in the 1960s; however, showing that the vector spaces it associated with systems were finite dimensional turned out to be very difficult. (This was not done until the mid 1990s, independently by Berthelot and ChristolMebkhout.) In my talk I will discuss an ``effectivity problem'' related to the finiteness of the rigid cohomology of a system of equations. 



May 10  Tue  Dr Anthony Field (Culham Laboratory)  Applied Mathematics Colloquium  
How to make 100 million a day, 100 million degrees C  the temperature at which plasma burns  


May 10  Tue  Sarah Whitehouse (Sheffield)  Topology Seminar  
15:10  Stable and unstable Ktheory operations  
Hicks Seminar Room J11  


May 11  Wed  Joe Chuang (Bristol)  Pure Maths Colloquium  
16:00  Representation theory with rhombus tilings  
Hicks Seminar Room J11  
Abstract: I'll discuss some joint work with Will Turner on certain algebras associated to tilings of the plane by rhombi. These `rhombal algebras' defined by Michael Peach were inspired by the representation theory of symmetric groups in positive characteristic. There is a close connection between the combinatorics of the tilings and the homological properties of the algebras. For example certain basic mutations of tilings correspond to equivalences of derived categories of modules. 



May 17  Tue  Mike Mandell (Cambridge)  Topology Seminar  
15:10  A Localization Sequence for the Algebraic KTheory of Topological KTheory  
Hicks Seminar Room J11  
Abstract: In many ways the algebraic Ktheory of ring spectra behaves like the algebraic Ktheory of traditional rings. One limitation is the lack of a general formulation of a devissage theorem. Recent work (joint with Andrew Blumberg) establishes one very special case of the devissage theorem. This case is sufficient to construct the localization sequence conjectured by Rognes relating the algebraic Ktheory of (complex) Ktheory, connective K theory, and the integers. 



May 18  Wed  Dr Sergey Nazarenko (Warwick)  Applied Mathematics Colloquium  
Turbulence of sea waves  


May 19  Thu  David Elworthy (Warwick)  
14:00  Stochastic Flows and Universal Connections  
K14  
Abstract: There are various places where the geometrical notion of a connection appears in stochastic analysis. In this expository talk I shall describe some of these, and show how they are related; first describing what they are and are useful for: in fact the more general notion of a non linear semi connection will be needed. For probabilists I'll indicate how they might (perhaps...) be useful for such problems as  trying to estimate the behaviour of an oil slick (on the surface of a curved planet, acted on by random forces) given the behaviour of one of its particles. For geometers/ topologists the constructions involved relate to the classifying spaces for gauge groups of subbundles of tangent bundles. This talk is mainly taken from joint work with Yves LeJan and XueMei Li, see http://xuemei.org/bib.html. 



May 24  Tue  Ieke Moerdijk (Sheffield)  Topology Seminar  
15:00  What do classifying spaces classify?  
Hicks Seminar Room J11  


May 25  Wed  Dr Nils Andersson (Southampton)  Applied Mathematics Colloquium  
Gravitationalwave asteroseismology  probing the extremes of physics  


May 25  Wed  Luis HernandezHernandez (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Fixed point degrees of equivariant maps of spheres  
Hicks Seminar Room J11  


May 25  Wed  Srikanth Iyengar (Nebraska)  Pure Maths Colloquium  
16:00  Levels in triangulated categories and perfect complexes over commutative rings  
Hicks Seminar Room J11  


May 31  Tue  Neil Strickland (Sheffield)  Topology Seminar  
15:10  The Rezk logarithm I  
Hicks Seminar Room J11  
Abstract: The Rezk logarithm is a natural map $(E^0X)^\times\rightarrow E^0X$ defined for all spaces $X$ and suitable generalised cohomology theories $E$. In many cases it is close to being an isomorphism. There is a simple definition using a functor constructed by Bousfield and Kuhn, but the thing that makes it usable is a theorem of Rezk relating it to the theory of power operations, and in particular the Hecke operators studied by Ando. This seminar will be the first of a series covering some of this material. 



Jun 7  Tue  Neil Strickland (Sheffield)  Topology Seminar  
15:10  The Rezk logarithm II  
Hicks Seminar Room J11  
Abstract: I will talk about generalized Moore spectra, K(n)localisation, and the BousfieldKuhn functor, all of which are ingredients in the definition of the Rezk logarithm. 



Jun 17  Fri  Hellen Colman (Wilbur Wright College, Chicago, USA)  Pure Maths Colloquium  
16:00  LusternikSchnirelmann category for orbifolds  
Hicks Seminar Room J11  
Abstract: We define and study a LusternikSchnirelmann theory for orbifolds. The orbifold category provides a new invariant of the homotopy type of the orbifold that gives a numerical measure of the complexity of the orbifold $X$. In particular, the orbifold category gives a lower bound on the number of critical points of any orbifold smooth function $f\colon X\rightarrow R$. We use equivariant methods to find upper and lower bounds on the orbifold category in terms of the orbifold resolution of the singular set. We obtain a generalization of the classical cohomological lower bound for orbifold category using the orbifold cohomology theory constructed by ChenRuan. 



Jul 5  Tue  Neil Strickland (Sheffield)  Topology Seminar  
15:10  The Rezk Logarithm II'  
Hicks Seminar Room J11  
Abstract: I will talk about generalized Moore spectra, K(n)localisation, and the BousfieldKuhn functor, all of which are ingredients in the definition of the Rezk logarithm. This will essentially be a repeat of the seminar I gave a few weeks ago when many people were away. 



Sep 20  Tue  Yoshi Maeda (Keio University, Japan)  Pure Maths Colloquium  
16:00  Deformation quantizations and gerbes  
Lecture Theatre 6  


Sep 28  Wed  Dr Stephen Davies (Leiden)  Applied Mathematics Colloquium  
Constraining GaussBonnet Dark Energy  


Sep 28  Wed  Peter Symonds (Manchester)  Pure Maths Colloquium  
16:10  Group actions on polynomial rings  
Hicks Seminar Room J11  
Abstract: We consider a polynomial ring $k[x_1,...,x_n]$ over a finite field $k$ and suppose that some finite group $G$ acts on it by linear substitutions. We want to understand the ring as a $kG$module. We present a structure theorem that describes this in a finite way. It has several notable corollaries, such as the fact that only finitely many indecomposable modules occur as summands (up to isomorphism) and the fact that we can write down an a priori bound on the degrees of the generators of the invariant subring. 



Oct 3  Mon  Tom Bridgeland (Sheffield)  
14:00  Mirror symmetry I  
Hicks Seminar Room J11  


Oct 4  Tue  Johann Sigurdsson (Sheffield)  Topology Seminar  
14:00  Duality in parametrized homotopy theory  
Hicks Seminar Room J11  
Abstract: I will describe formal structure enjoyed by the parametrized stable homotopy categories and how one can encode it into a single bicategory. I will then discuss duality theory from that perspective and show how it gives simple conceptual proofs of generalizations of various known duality phenomena such as Atiyah duality and the Wirthmuller and Adams equivalences. The talk should be accessible to everyone. 



Oct 5  Wed  Dr Steven Tobias (Leeds)  Applied Mathematics Colloquium  
The role of spectra in dynamo theory  does meanfield modelling make any sense?  


Oct 5  Wed  Graham Everest (East Anglia)  Pure Maths Colloquium  
16:00  Bilinear Recurrence Sequences  
Hicks Seminar Room J11  


Oct 7  Fri  Yukinobu Toda (Tokyo)  
14:00  Deformations and FourierMukai transform  
Hicks Seminar Room J11  


Oct 10  Mon  Tom Bridgeland (Sheffield)  
14:00  Mirror symmetry II  
Hicks Seminar Room J11  


Oct 11  Tue  Johann Sigurdsson (Sheffield)  Topology Seminar  
14:00  Duality in parametrized homotopy theory  
Hicks Seminar Room J11  


Oct 12  Wed  Rapha (Leeds)  Pure Maths Colloquium  
16:00  Dunkl operators and Hecke algebras  
Hicks Seminar Room J11  
Abstract: The first parts of my talk will be very elementary. I will introduce a deformation of the ordinary derivation of real functions of one variable. I will discuss the corresponding operator on polynomials (for which values of the deformation parameter are there non constant polynomials killed by the operator ?) and on analytic functions (spectrum of the operator, eigenfunctions as Bessel functions). Then, I will switch to the dimension $n$ case, where one has a commuting family of operators deforming the $d/dx_i$ (the Dunkl operators). I will focus on the action on polynomial functions of $n$ variables and explain how this is controlled by an algebra deforming the algebra of polynomial differential operators (a doubly degenerate double affine Hecke algbra). This leads to the study of representations of this algebra. I will describe how the representation theory of this algebra is studied, in analogy with the representation theory of the Lie algebra $gl_n(\mathbb{C})$. This last part brings a lot of exciting mathematics:




Oct 13  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Overview of the Beilinson conjectures.  
Hicks Seminar Room J11  


Oct 14  Fri  Victor Snaith (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Monomial Representations  
Hicks Seminar Room J11  


Oct 14  Fri  Moty Katzman (Sheffield)  
14:00  Ideals of minors of matrices with indeterminate entries  


Oct 17  Mon  Tom Bridgeland (Sheffield)  
14:00  Mirror symmetry III  
Hicks Seminar Room J11  


Oct 18  Tue  Simon Willerton (Sheffield)  Topology Seminar  
14:00  The derived category of sheaves on a complex manifold from a representation theory perspective  
Hicks Seminar Room J11  
Abstract: I will try to explain how the derived category of sheaves on a complex manifold (which I will remind you of) looks a lot like the representation category of a finite group. This will be motivated by ideas from topological field theory. 



Oct 19  Wed  Karima Khusnutdinova (Loughborough)  Applied Mathematics Colloquium  
The effect of bubbles on internal waves  


Oct 19  Wed  Alexander Stasinski (University of East Anglia)  Pure Maths Colloquium  
16:00  Representations of reductive groups over finite rings  
Hicks Seminar Room J11  
Abstract: Let $F$ be a local field with finite residue field, ring of integers $O$, and maximal ideal $p$. Let $G$ be a reductive group scheme over $O$ (e.g. $G=GL_n$). We present an approach to the study of representations of the finite groups $G_{r}:=G(O/p^r)$, which for $r=1$ coincides with the theory of Deligne and Lusztig. One reason why such a study is of interest is the close connection between the representation theory of the groups $G_{r}$, and the representation theory of the group $G(F)$. One of the few cases where the representations of $G_{r}$ are known for all $r;eq1$, is when $G=GL_{2}$. This is due to several people, including Kutzko, and the method used is purely algebraic, and quite different from our geometric approach. We show how the two methods can be linked, and in particular how the algebraic method can be used to analyse representations constructed geometrically. 



Oct 20  Thu  Victor Snaith (Sheffield)  
12:10  Overview of the Beilinson Conjectures II  
Hicks Seminar Room J11  


Oct 25  Tue  David Gepner (Sheffield)  Topology Seminar  
14:00  Equivariant elliptic cohomology  
Hicks Seminar Room J11  


Oct 26  Wed  Reza Raoufi and Alan Zinober (Sheffield)  Applied Mathematics Colloquium  
$C^3$ = Chaos, Cryptography and Control  


Oct 26  Wed  Dietrich Notbohm (University of Leicester)  Pure Maths Colloquium  
16:00  Homology decompositions and applications  
Hicks Seminar Room J11  
Abstract: A homolgy decomposition is a way to build a space out of 'simpler' space. A CW complexes is given an iterated building process based on spheres and discs where as the gluing data for homology decompositions is encoded in a functor defined on a 'nice' category with values in the category of topological spaces, and where all simpler spaces are glued together in one step. Homology decompositions are one of the major tools to understand the homotopy theory of classifying spaces. We will apply these ideas in several much more algebraic contexts, StanleyReisner algebras associated to simplicial complexes, invariant theory and group cohomology. 



Oct 27  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Overview of the Beilinson conjectures III.  
Hicks Seminar Room J11  


Oct 28  Fri  Paul Buckingham (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Sheaf Cohomology and hypercohomology  
Hicks Seminar Room J11  


Oct 28  Fri  Almar Kaid (Sheffield)  Algebra / Algebraic Geometry seminar  
14:00  Unitarily graded field extensions  
Hicks Seminar Room J11  


Nov 2  Wed  Prof. Howard Wilson (York)  Applied Mathematics Colloquium  
Explosive instabilities in laboratory fusion plasmas  


Nov 2  Wed  Marcus Linckelmann (Aberdeen)  Pure Maths Colloquium  
16:00  Fusion Systems and Modular Representation Theory  
Hicks Seminar Room J11  
Abstract: The $p$local approach to finite group theory tries to understand the structure of a finite group in terms of one of its Sylow$p$subgroups $P$ (they are all isomorphic, so it doesn't matter which one we take) and the way in which $P$ is embedded into $G$. This approach goes well back to the early stages of the theory, illustrated by theorems of Burnside and Frobenius, and plays an important role in the context of the classification of finite simple groups. One can describe the plocal structure of $G$ in terms of a category, the fusion system of $G$. As a consequence of work of Alperin and Broue around 1980 it appears that categories with very similar formal properties occur also in modular representation theory, prompting Puig in the 1990's to formalise the notion of fusion systems independently of finite groups and Benson to speculate whether any such fusion system gives rise to a topological space which would play the role of classifying space of the group. Broto, Levi and Oliver developed in recent years the precise framework for topological spaces arising in this way  giving a sense to the concept of classifying spaces of finite groups which don't exist... 



Nov 3  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Overview of Beilinson's conjectures IV  
Hicks Seminar Room J11  


Nov 4  Fri  Sam Marsh (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  TBA  
Hicks Seminar Room J11  


Nov 4  Fri  David Jordan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:00  Poisson algebras and modules: a case study.  
Hicks Seminar Room J11  


Nov 9  Wed  Everett Howe (Center for Communications Research, San Diego)  Pure Maths Colloquium  
16:00  
Hicks Seminar Room J11  


Nov 10  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Overview of Beilinson's conjectures V  
Hicks Seminar Room J11  


Nov 11  Fri  Victor Snaith (Sheffield)  Snaith seminar  
10:00  The Arf Invariant One Problem Part I  
Hicks Seminar Room J11  


Nov 11  Fri  David Barnes (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Theory of Representations and Stable Homotopy  
Hicks Seminar Room J11  
Abstract: The speaker has been overheard referring to this subject (acronymoniously)as T.R.A.S.H. 



Nov 11  Fri  Victor Snaith (Sheffield)  Snaith seminar  
14:00  The Arf Invariant One Problem Part II  
Hicks Seminar Room J11  


Nov 14  Mon  Prof. Stanley L Jaki (Seton Hall)  Applied Mathematics Colloquium  
A late awakening with a nightmare  


Nov 14  Mon  Stanley L. Jaki (Seton Hall University)  Pure Maths Colloquium  
16:00  A late awakening with a nightmare  
LT5  
Abstract: According to Godel's theorem, formulated in 1930, no non trivial theory of arithmetic can have its proof of consistency in terms of the presuppositions of the theory itself. This means that it is not possible to form a final form of mathematics that would be its sole form which is also necessarily true. Since physics has to be heavily mathematical, this also means the end of hopes that a final physical theory could ever be formulated. Contrary to a recent claim of Prof Hawking, this does not mean of the end of physics, though it constitutes a death blow at those hopes, often proposed with great arrogance. Godel's theorem is an assurance that the work of physicists will go on to no end. 



Nov 15  Tue  Andrew Stacey (Sheffield)  Topology Seminar  
14:00  Delooping Moravian Maps  
Hicks Seminar Room J11  
Abstract: One of the pieces of baggage that comes with a graded cohomology theory is the family of operations. These are selfmaps of the cohomology groups obeying certain obvious naturality conditions. There are two main types of operation: stable and unstable. An unstable operation acts only on the cohomology groups of a particular degree whilst a stable operation acts on the cohomology groups of any degree compatibly with the suspension isomorphism. It is clear, therefore, that a stable operation defines a family of unstable ones. However, even if one knows that an unstable operation came from a stable one it may not be easy to reconstruct that stable operation. What is remarkable about the Morava Ktheories is that there is a straightforward way to do this. The "delooping" of the title refers to the fact that operations are closely linked to maps between certain spaces and spectra associated to the cohomology theory. In this language, the claim is that there is a simple way to convert an arbitrary map between the representing spaces of the Morava Ktheories into an infinite loop map. The mathematics involved is astonishingly simple and I shall endeavour to keep the exposition in a similar vein. Thus the prerequisites are minimal: a familiarity with cohomology theories and their links with spectra. This work is joint with Sarah Whitehouse and is funded as part of the EPSRC project on operations in Morava Ktheories. 



Nov 16  Wed  Dr A Thyagaraja (Culham Laboratory)  Applied Mathematics Colloquium  
Mesoscale electromagnetic turbulence in tokamaks  


Nov 16  Wed  Mark Watkins (Bristol)  Pure Maths Colloquium  
16:00  Special values of Lfunctions: a meeting place of algebra and analysis.  
Hicks Seminar Room J11  


Nov 18  Fri  Ian Young (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Lfunctions and elliptic curves  
Hicks Seminar Room J11  


Nov 18  Fri  David Jordan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:00  Poisson algebras and modules: a case study II  
Hicks Seminar Room J11  


Nov 22  Tue  Ruben Sanchez (Sheffield)  Topology Seminar  
14:00  Classifying spaces for proper actions and the BaumConnes Conjecture  
Hicks Seminar Room J11  
Abstract: I will explain how to generalize the ordinary classifying space of a group G to actions with finite stabilizers. The corresponding classifying space appears in the BaumConnes Conjecture, which identifies two objects associated to G, one analytical and one topological. The analytical one is the Ktheory of the reduced $C^*$algebra of G, and the topological one is the equivariant Khomology of this classifying space. I will describe how to use Bredon homology and a spectral sequence to obtain the topological side of BaumConnes. Then I would like to explain how to do this for the groups $SL(3,\mathbb{Z})$ and for some Coxeter groups. The talk may suit two sessions, so if people are not too unhappy, I may also talk the following week. 



Nov 23  Wed  Prof. Yurii Sergeev (Newcastle)  Applied Mathematics Colloquium  
Tracer particles in turbulent helium II at low temperatures  


Nov 23  Wed  Paul Buckingham (Sheffield)  
01:30  Serre's Modularity Conjecture "Recipe for the weight"  
Hicks Seminar Room J11  


Nov 23  Wed  Aaron Lauda (Cambridge)  Pure Maths Colloquium  
16:00  Frobenius algebras and thick tangles  
Hicks Seminar Room J11  
Abstract: In topological quantum field theory one is interested in studying functors from a topological category of $n$dimensional cobordisms into the category of vector spaces. In two dimensions such functors are very well understood. In fact, specifying a (symmetric monoidal) functor from the 2dimensional cobordism category 2Cob into Vect is equivalent to specifying a commutative Frobenius algebra. This makes the study of 2dimensional TQFT's particularly simple. Recent developments in string theory have prompted many to consider topological quantum field theories using a more interesting version of the $2$dimensional cobordism category, namely one that allows for cobordisms between $1$manifolds with boundary. In this talk I will define a category of planar cobordisms between `open strings' and show that functors from this category into Vect are equivalent to (not necessarily commutative) Frobenius algebras. This result arises naturally by considering adjunctions in 2 categories. If time permits, I will also sketch how this process can be generalized to higherdimensional surfaces using higherdimensional category theory. This talk is intended to be accessible; all concepts from higherdimensional category theory will be introduced in the talk. 



Nov 24  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Beilinson conjectures VI: a proof of cases of the Lichtenbaum conjecture.  
Hicks Seminar Room J11  
Abstract: This (possibly!!!  see the abstract to Beilinson VII) final lecture in this semester's series on the Beilinson conjectures culminates with my ( AD 2000) proof of Lichtenbaum's conjecture for the order of $K_{4k}(Z)$. Mention will also be made of my new formula for the Borel Beilinson regulator in dimension 3. 



Nov 25  Fri  MaryJane Strong (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Splittings of cohomology theories  
Hicks Seminar Room J11  


Nov 25  Fri  David Jordan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:05  Poisson algebras and modules: a case study III  
Hicks Seminar Room J11  


Nov 25  Fri  Neil Strickland (Sheffield)  
14:10  Cobordism and formal power series  
Lecture Room 6  
Abstract: We will discuss the basic definitions of cobordism theory, and outline a proof of the following result of Thom: the unoriented cobordism ring $MO_*$ is given by $$ \mathbb{Z}/2[x_2,x_4,x_5,x_6,x_8,x_9,\ldots], $$ with one generator $x_k$ in each degree $k$ not of the form $2^i1$. There will be many pretty pictures. 



Nov 29  Tue  Ruben Sanchez (Sheffield)  Topology Seminar  
14:00  Equivariant Khomology for $SL(3,\mathbb{Z})$ and Coxeter groups  
Hicks Seminar Room J11  
Abstract: I will show how to compute the topological side of the BaumConnes conjecture for $SL(3,\mathbb{Z})$ and some Coxeter groups. I will put some illustrative pictures. 



Nov 29  Tue  Iakovos Androulidakis (Z)  
16:10  Realisation of singular foliations by Lie groupoids  
Hicks Seminar Room J11  
Abstract: Lie groupoids generalise at the same time the notion of a Lie group and a manifold. Every Lie groupoid defines a foliation in a canonical way, which may well have singularities, and in this sense the groupoid can be thought of as a desingularization of this foliation. We address the converse problem in this talk, namely whether every singular foliation in the sense of Stefan and Sussmann comes from a Lie groupoid. In particular we present a construction that provides a positive answer, and discuss its implications in noncommutative geometry and quantization. 



Nov 30  Wed  Dr Kiril Kuzanyan (Leeds)  Applied Mathematics Colloquium  
Helicity and Solar dynamo: confront theory and observations  


Nov 30  Wed  Ivan Smith (Cambridge)  Pure Maths Colloquium  
16:00  Knots, matrices and symplectic topology  
Hicks Seminar Room J11  


Dec 1  Thu  Victor Snaith (Sheffield)  Snaith seminar  
12:10  Beilinson VII: Borel's regulator, the final moppingup!!  
Hicks Seminar Room J11  
Abstract: I imagine that Beilinson VI will cover the Lichtenbaum conjecture but not the formula for Borel's regulator  so Beilinson VII is reserved for the latter, if necessary. It will be the last in the series! 



Dec 2  Fri  Luis HernandezHernandez (Sheffield)  Pure Maths Postgraduate Seminar  
11:10  Cohomology of Projective Bundles  
Hicks Seminar Room J11  


Dec 2  Fri  David Jordan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:05  Possion algebras and modules: a case study IV  
Hicks Seminar Room J11  


Dec 7  Wed  Kari Ragnarsson (Aberdeen)  Pure Maths Colloquium  
16:00  Homotopy classifications of pcompleted classifying spaces  
Hicks Seminar Room J11  
Abstract: In algebraic topology one typically applies powerful algebraic invariants to encode homotopy properties of topological spaces. In certain cases it is possible and useful to reverse this process by assigning a space to an algebraic object. An instance of this is the assignment to a finite group $G$ of a classifying space $BG$, whence the group $G$ can be recovered as the fundamental group. Furthermore, group homomorphisms between finite groups correspond bijectively to homotopy classes of maps between their classifying spaces. In this talk I will discuss how this correspondence changes when we focus on properties relative to a prime $p$. Topologically this means applying the $p$completion functor to $BG$. I will present three classification theorems for $p$completed classifying spaces of finite groups. First, the unstable classification, predicted by Martino Priddy and proved by Oliver, which classifies the homotopy type of the $p$completed classifying space of $G$ via the fusion system of $G$. Second, the stable classification, due to MartinoPriddy, which classifies the stable homotopy type of the pcompleted classifying space of $G$ via weaker data, which loosely speaking can be regarded as a linearisation of the fusion system. Finally, the partially stable classification, which links the unstable and stable classifications. This is the surprising result that, by keeping track of inclusions of Sylow subgroups, the stable homotopy type of the $p$completed classifying space of $G$ can again be classified via the fusion data of $G$. This classification also gives a simple description of maps realising stable homotopy equivalences (while preserving the inclusions of Sylow subgroups). 



Dec 9  Fri  Yukinobu Toda (Tokyo)  Algebra / Algebraic Geometry seminar  
16:00  $A_{\infty}$ structures and FourierMukai transforms (An introduction to A. Polishchuk's work)  
Hicks Seminar Room J11  
Abstract: First I will give an introduction of $A_{\infty}$ algebras and $A_{\infty}$ categories. Then we combine them with the techniques of FourierMukai transforms, and approach the problem of describing BrillNoether loci. These are generalizations of theta divisors of Jacobian of curves, and we will see that $A_{\infty}$ techniques can be applied to some classical problems in algebraic geometry. 



Dec 12  Mon  Alfonso GraciaSaz (Berkeley)  
16:10  The symbol of a function of an operator (or How finding the right notation solves half the problem)  
Hicks Seminar Room J11  
Abstract: In the quantum description of a physical system, the observables (e.g. the energy) are represented by operators on a Hilbert space. In the classical description, they are represented by functions on phase space. Weyl quantization provides a bijection between quantum and classical observables. To every operator (quantum) $\widehat{A}$, we associate a function (classical) $A$, called its symbol. We consider the following problem. Let $\widehat{A}$ be an operator with symbol $A$ and let $f$ be a smooth function. Then $\widehat{B}:=f(\widehat{A})$ is another operator, with symbol $B$. What is $B$ in terms of $A$? We will provide an answer to this question in the form of a formula ``à la Feynman'', i.e. a power series whose terms are labeled by diagrams. This has various applications to quantum mechanics. No knowledge of physics will be assumed. The talk will come with a moral: There is no difficult calculation, only unfortunate notations. 



Dec 13  Tue  Dr Fay Dowker (Blackett Laboratory, Imperial College)  Applied Mathematics Colloquium  
Causal Set Phenomenology  


Dec 13  Tue  Halvard Fausk (Oslo)  Topology Seminar  
14:00  tmodel structures  
Hicks Seminar Room J11  
Abstract: For every stable model category $M$ with a certain extra structure, we produce an associated model structure on the procategory $Pro(M)$ and a spectral sequence, analogous to the AtiyahHirzebruch spectral sequence, with reasonably good convergence properties for computing in the homotopy category of $Pro(M)$. Our motivating example is the category of prospectra. The extra structure referred to above is a tmodel structure. This is a rigidification of the usual notion of a tstructure on a triangulated category. A tmodel structure is a proper simplicial stable model category $M$ with a tstructure on its homotopy category together with an additional factorization axiom. 



Dec 13  Tue  Fay Dowker (Imperial College)  Pure Maths Colloquium  
16:00  Causal Set Phenomenology  
Lecture Theatre G  
Abstract: The hypothesis that the discrete substructure of spacetime is a causal set suggests a straightforward model building technique: invent phenomenological dynamics for matter (particles or fields) on a background causal set that is well approximated by our continuum spacetime. These models can be analysed to see if they predict observable eviations from continuum models. I will describe two examples of such models: "particle swerves" and a model of detector response to the scalar field of a scalar charge source. 



Dec 14  Wed  Jon Woolf (Liverpool)  Pure Maths Colloquium  
16:00  Signatures and Witt spaces, or, why life is simpler with singularities.  
Hicks Seminar Room J11  
Abstract: The signature of a manifold is an important invariant: it is the basic obstruction to a manifold being the boundary of a manifold of one dimension higher. The talk will survey some classical results for computing signatures and explain how, by introducing a notion of signature for certain singular spaces, we can obtain very geometric proofs and significant extensions of these results. 



Jan 16  Mon  Matthew Ando (UrbanaChampaign)  Chromatic homotopy  
16:00  TBA  
Hicks Seminar Room J11  


Jan 23  Mon  Ruben Sanchez (Sheffield)  Chromatic homotopy  
16:00  Orthogonal Spectra II  
Hicks Seminar Room J11  


Jan 27  Fri  Johann Sigurdsson (Sheffield)  Chromatic homotopy  
16:00  Structured Spectra  
Hicks Seminar Room J11  
Abstract: Now that we have good geometric models for the stable homotopy category it is time to construct spectra representing particular cohomology theories. The point is to do that in such a way that interesting structure of cohomology theories, such as pairings, is already reflected in structure on the spectra. I will in particular focus on the Thom spectra representing the various cobordism theories. 



Jan 30  Mon  Johann Sigurdsson (Sheffield)  Chromatic homotopy  
16:00  Structured Spectra II  
Hicks Seminar Room J11  


Feb 3  Fri  Sam Marsh (Sheffield)  Chromatic homotopy  
16:00  Complex Oriented Cohomology Theories I  
Hicks Seminar Room J11  


Feb 6  Mon  Sam Marsh (Sheffield)  Chromatic homotopy  
16:00  Complex Oriented Cohomology Theories II  
Hicks Seminar Room J11  


Feb 8  Wed  Dr Thomas Neukirk (St Andrews)  Applied Mathematics Colloquium  
Current Buildup in Topologically Simple Magnetic Fields  


Feb 8  Wed  Alexander Odesskii (Machester)  Pure Maths Colloquium  
16:00  Elliptic algebras  
Hicks Seminar Room J11  
Abstract: The talk is devoted to associative Ngraded algebras presented by n generators and n(n1)/2 quadratic relations and satisfying the socalled PoincareBirkhoffWitt condition (PBWalgebras). We consider examples of such algebras depending on two continuous parameters (namely, on an elliptic curve and a point on this curve) which are flat deformations of the polynomial ring in n variables. Diverse properties of these algebras will be described, together with their relations to integrable systems, deformation quantization, moduli spaces and other directions of modern investigations. 



Feb 10  Fri  James Cranch (Sheffield)  Chromatic homotopy  
16:00  The Lazard Ring and Quillen's Theorem  
Hicks Seminar Room J11  


Feb 13  Mon  James Cranch (Sheffield)  Chromatic homotopy  
16:00  The Lazard Ring and Quillen's Theorem, II  
Hicks Seminar Room J11  


Feb 15  Wed  Prof Alexander B. Movchan (Liverpool)  Applied Mathematics Colloquium  
Asymptotic analysis of solutions to singularly perturbed problems in multistructures  


Feb 15  Wed  Victoria Hinchcliffe (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  The Filter Dimension and the Inequality of Bernstein  
Hicks Seminar Room J11  


Feb 15  Wed  Nikita Markarian (Sheffield)  Algebra / Algebraic Geometry seminar  
14:00  Hochschild homology, Atiyah classes and RiemannRoch theorem I  
Hicks Seminar Room J11  


Feb 15  Wed  Balazs Szendroi (Oxford)  Pure Maths Colloquium  
16:00  The amazing partition function of local P^1  
Hicks Seminar Room J11  
Abstract: To a manifold M, string theory associates its topological partition function, a finite dimensional approximation to a complicated path integral on M. One of the simplest cases when this function can be computed explicitly is that of local P^1, a certain complex threefold fibred over the projective line. Its partition function can be written in six or seven different ways, as infinite sum or infinite product, related to GromovWitten theory, DonaldsonThomas theory, the combinatorics of partitions, ChernSimons theory of knots... The talk will introduce these ideas in elementary terms. 



Feb 17  Fri  Holger Brenner (Sheffield)  Chromatic homotopy  
16:00  Introduction to Algebraic Geometry  
Hicks Seminar Room J11  


Feb 20  Mon  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Schemes, Sheaves and Topoi  
Hicks Seminar Room J11  
Abstract: We continue our introduction to derived algebraic geometry. In particular, we will define schemes, sheaves, and topoi (not necessarily in that order!) and, time permitting, consider possible homotopytheoretic generalizations. 



Feb 22  Wed  Prof Roger Grimshaw (Loughborough)  Applied Mathematics Colloquium  
Internal solitary waves and undular bores in the atmosphere and ocean  


Feb 22  Wed  Zacky Choo (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Borel's Regulator  
Hicks Seminar Room J11  


Feb 22  Wed  Nikita Markarian (Sheffield)  Algebra / Algebraic Geometry seminar  
14:00  Hochschild homology, Atiyah classes and RiemannRoch theorem II  
Hicks Seminar Room J11  


Feb 22  Wed  Alastair King (University of Bath)  Pure Maths Colloquium  
16:00  Moduli of sheaves from moduli of Kronecker modules  
Hicks Seminar Room J11  


Feb 24  Fri  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Schemes, Sheaves and Topoi II  
Hicks Seminar Room J11  


Mar 1  Wed  Dr Andrew Soward (Exeter)  Applied Mathematics Colloquium  
Nonaxisymmetric $\alpha^2\Omega$dynamo waves in thin stellar shells  


Mar 1  Wed  Alastair Hamilton (University of Bristol)  Pure Maths Colloquium  
16:00  Graph homology classes via infinityalgebras  
Hicks Seminar Room J11  
Abstract: I will discuss the role played by certain aspects of quantum field theory such as the Feynman calculus and the BatalinVilkovisky formalism in the construction of graph homology and cohomology classes, as introduced by Kontsevich in his 92/93 papers. I will also give the first example of a nontrivial pairing between a graph homology and cohomology class which arises from the evaluation of a superintegral, more than ten years since the idea was first proposed by Kontsevich. 



Mar 3  Fri  David Gepner (Sheffield)  Chromatic homotopy  
16:00  The Functor of Points Approach to Algebraic Geometry  
Hicks Seminar Room J11  
Abstract: We will illustrate our ``functor of points'' approach to algebraic geometry through a number of concrete examples. In particular, we will see when a subfunctor of a scheme is itself a (closed or open) subscheme, and we will determine the functor represented by ndimensional projective space. 



Mar 6  Mon  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Quasicoherent Sheaves  
Hicks Seminar Room J11  
Abstract: We will introduce the notion of a (quasi)coherent sheaf on a scheme. The (quasi)coherent sheaves play a central role in algebraic geometry, particularly in cohomology theory. We will illustrate with examples of coherent sheaves on projective space. 



Mar 8  Wed  Dr Robert Walsh (Central Lancashire)  Applied Mathematics Colloquium  
Taking the Sun's temperature: modelling the pros and cons of EUV rastering spectrometers vs narrowband imagers  


Mar 8  Wed  Marc Lackenby (Oxford)  Pure Maths Colloquium  
16:00  Property tau  
Hicks Seminar Room J11  
Abstract: How can one construct computer networks without bottlenecks? Is there a method of efficiently shuffling a pack of cards? How does the spectrum of the Laplacian on a manifold behave under finitesheeted covers? How can one detect `large' groups? Do hyperbolic 3manifolds contain essential surfaces? In my talk, I will show how these questions are all related to an intriguing concept known as `Property tau'. 



Mar 9  Thu  Holger Brenner (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Grothendieck topologies and closure operations for ideals I  
Hicks Seminar Room J11  


Mar 10  Fri  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Quasicoherent Sheaves  
Hicks Seminar Room J11  


Mar 13  Mon  Ieke Moerdijk (Sheffield)  Chromatic homotopy  
16:00  Operads, Dendroidal Sets and Weak Categories  
Hicks Seminar Room J11  


Mar 15  Wed  Prof Leo Brevdo (University of the Mediterranean (Marseille, France))  Applied Mathematics Colloquium  
Absolute instability of spatially developing flows and media  


Mar 15  Wed  Bruce Bartlett (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  2representations of groups  
Hicks Seminar Room J11  
Abstract: There is a jigsaw puzzle P of closely related ideas that revolve around topological quantum field theory, n categories, gerbes, elliptic cohomology, knot theory, and higher gauge theory. Unfortunately, I am not qualified to talk about P. I will however attempt to address one infinitesimal piece of P, which is called the "2category of 2representations of a finite group. 



Mar 15  Wed  Jonathan Jordan (University of Sheffield, dept. of Probability and Statistics)  Pure Maths Colloquium  
16:00  Spectral properties of fractal graphs  
Hicks Seminar Room J11  


Mar 16  Thu  Holger Brenner (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Grothendieck topologies and ideal closure operations II  
Hicks Seminar Room J11  


Mar 17  Fri  Ruben Sanchez (Sheffield)  Chromatic homotopy  
16:00  Homotopy Limits and Colimits  
Hicks Seminar Room J11  


Mar 20  Mon  Ieke Moerdijk (Sheffield)  Chromatic homotopy  
16:00  Operads, Dendroidal Seta and Weak Categories.  
Hicks Seminar Room J11  


Mar 22  Wed  James Cranch (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Rational Morava Etheory of symmetric groups  
Hicks Seminar Room J11  


Mar 22  Wed  Frances Kirwan (Oxford)  Pure Maths Colloquium  
16:00  Moduli spaces of bundles over curves revisited  
Hicks Seminar Room J11  
Abstract: Several decades ago the Betti numbers of the moduli spaces of stable vector bundles (with fixed mutually coprime rank and degree) over a Riemann surface were found, first by Harder and Narasimhan using numbertheoretic methods and counting objects defined over finite fields, and soon after by Atiyah and Bott using YangMills theory and equivariant Morse theory. This talk will link these two approaches and describe some more recent results on the geometry of the moduli spaces. 



Mar 23  Thu  Holger Brenner (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Grothendieck topologies and ideal closure operations III  
Hicks Seminar Room J11  


Mar 24  Fri  Ruben Sanchez (Sheffield)  Chromatic homotopy  
16:00  Homotopy Limits and Colimits, II  
Hicks Seminar Room J11  


Mar 27  Mon  Ieke Moerdijk (Sheffield)  Chromatic homotopy  
16:00  Operads, dendroidal sets and weak categories III  
Hicks Seminar Room J11  


Mar 29  Wed  Dr Jacques Vanneste (Edinburgh)  Applied Mathematics Colloquium  
Wave radiation by slow flows  


Mar 29  Wed  Almar Kaid (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Syzygy Bundles and the Weak Lefschetz Property  
Hicks Seminar Room J11  


Mar 29  Wed  Tom Leinster (Glasgow)  Pure Maths Colloquium  
16:00  Another look at Euler characteristic  
Hicks Seminar Room J11  
Abstract: Far beyond the realm where we can count "vertices minus edges", there are spaces that, nevertheless, appear to have a well defined Euler characteristic. For example, the Julia set of any rational function f seems to have an Euler characteristic, a number giving basic information about the dynamical behaviour of f. But to define the Euler characteristic of such spaces, we first need to define the Euler characteristic of a category. This involves generalizing the Mobius inversion formula of classical number theory. We'll see, for instance, that the Euler characteristic of the category of finite sets and bijections is e = 2.718... . Throughout, our motto is: "Euler characteristic is generalized cardinality". 



Mar 31  Fri  Ruben Sanchez (Sheffield)  Chromatic homotopy  
16:00  Homotopy Limits and Colimits III  
Hicks Seminar Room J11  


Apr 26  Wed  Dr Dave Roscoe (Sheffield)  Applied Mathematics Colloquium  
Redshift phenomenology: A review of Napier's analysis  


Apr 26  Wed  Caroline Series (Warwick)  Pure Maths Colloquium  
16:00  Taming the unruly hyperbolic jungle  
Hicks Seminar Room J11  
Abstract: The last few years have seens some spectacular developments in our understanding of hyperbolic 3manifolds. The title of my talk is taken from a recent article in Science magazine on this topic. The problems are equivalent to much simpler sounding questions about what happens when you iterate Mobius maps. I will give an overview of the background and the significance of the new developments, illustrated with many pictures from our book Indra's Pearls (Mumford, Series and Wright, CUP 2002). 



Apr 27  Thu  Georg Struth (Sheffield, Department of Computer Science)  Algebra / Algebraic Geometry seminar  
15:10  Kleene algebras and program analysis  
Hicks Seminar Room J11  
Abstract: Kleene algebras are noncommutative idempotent semirings with an additional operation for iteration or reflexive transitive closure. They have recently received considerable attention as foundational structures in computer science and for their suitability in different application areas. In this talk I will discuss the basics of Kleene algebras and related structures. I will also try to point out the general benefits of algebraic approaches to software analysis and verification and survey a number of applications in the analysis of programs and software systems. 



Apr 28  Fri  James Cranch (Sheffield)  Chromatic homotopy  
16:00  Introduction to Stacks  
Hicks Seminar Room J11  


May 2  Tue  Neil Dummigan (Sheffield)  
11:00  Number Theory Seminar "Modular degrees of elliptic curves"  
Hicks Seminar Room J11  
Abstract: In the first talk I'll look at Neron models of abelian varieties, the Tate padic uniformisation of elliptic curves and the modular parametrisations of elliptic curves over the rationals. In the second talk I'll look at the description of the special fiber of the Neron model of the Jacobian of a curve, in terms of the special fiber of a regular model of the curve. Then I'll use all this to prove something about the degrees of modular parametrisations. 



May 3  Wed  Dr Sergei Molokov (Coventry)  Applied Mathematics Colloquium  
Interfacial instability in a twolayer system with transverse electric current  


May 3  Wed  Rajender Adibhatla (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Deformations of Galois representations  
Hicks Seminar Room J11  


May 3  Wed  Simon Donaldson (Imperial College)  Pure Maths Colloquium  
16:00  Differential geometry on toric varieties  
Hicks Seminar Room J11  


May 5  Fri  James Cranch (Sheffield)  Chromatic homotopy  
16:00  Introduction to Stacks, II  
Hicks Seminar Room J11  


May 8  Mon  James Cranch (Sheffield)  Chromatic homotopy  
16:00  Introduction to Stacks, III  
Hicks Seminar Room J11  


May 10  Wed  Prof Basil Hiley (Birkbeck College)  Applied Mathematics Colloquium  
Quantum Field Theory and the Bohm Model: the Role of the Photon  


May 10  Wed  Anthony Hignett (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Stable cooperations in complex Ktheory  
Hicks Seminar Room J11  


May 10  Wed  Fran Burstall (Bath)  Pure Maths Colloquium  
16:00  Harmonic Gauss maps  
Hicks Seminar Room J11  
Abstract: I shall give an overview for nonexperts of the modern theory of harmonic maps and how it applies to questions of classical (and sometimes unfashionable) differential geometry via an appropriate notion of Gauss map. 



May 12  Fri  James Cranch (Sheffield)  Chromatic homotopy  
16:00  Introduction to Stacks, IV  
Hicks Seminar Room J11  


May 15  Mon  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Higher and Derived Stacks, I  
Hicks Seminar Room J11  


May 16  Tue  Paul Buckingham (Sheffield)  
11:00  TBA  this will be a number theory seminar  
Hicks Seminar Room J11  
Abstract: This talk will deal with the annihilator ideal of the group ring of a Galois group action on a cyclotomic class group. 



May 17  Wed  Prof Chris Eilbeck (Heriot Watt)  Applied Mathematics Colloquium  
Breathers in discrete systems  


May 17  Wed  Panagiotis Tsaknias (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Modular forms and Fermat's Last Theorem  
Hicks Seminar Room J11  


May 18  Thu  Rodney Sharp (Sheffield)  Algebra / Algebraic Geometry seminar  
15:00  Artinian modules with a Frobenius action or What I did in my Study Leave  
Hicks Seminar Room J11  


May 18  Thu  Luca Stefanini (Zurich)  
16:00  Differential Geometry Seminar Integration of LAGroupoids  
Hicks Seminar Room J11  
Abstract: Many problems regarding second order differential geometry, Poisson geometry, Lie algebroids and Lie groupoids can be formulated in terms of double structures such as double Lie groupoids, LAgroupoids and double Lie groupoids. After overviewing the key facts in Lie theory for Lie algebroids and Lie groupoids, it shall be presented how Lie's theorems extend for LAgroupoids and double Lie groupoids. Apart from a few technicalities, the suitable generalisations are obtained using simple functorial arguments. A few applications to integrability and duality of Poisson groupoids will be briefly described. Note added by Kirill : An LAgroupoid is a groupoid object in the category of Lie algebroids. These structures arise by infinitesimalizing double Lie groupoids, but they also arise in nature as the cotangent bundles of Poisson Lie groups. In that case, they are intermediate between the Drinfel'd double of the corresponding Lie bialgebra and the matched pairs of Lie groups, or symplectic double groupoids, which provide global forms of Poisson Lie groups. 



May 19  Fri  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Higher and Derived Stacks, II  
Hicks Seminar Room J11  


May 24  Wed  Dr David Roscoe (Sheffield)  Applied Mathematics Colloquium  
Electrodynamics: Old theory in a new light  


May 26  Fri  David Gepner (Sheffield)  Chromatic homotopy  
16:00  Higher and Derived Stacks, III  
Hicks Seminar Room J11  


Jun 1  Thu  Dr Manuel Blickle (Essen)  Algebra / Algebraic Geometry seminar  
15:00  Wittrational singularities and rational points  
Hicks Seminar Room J11  
Abstract: I am reporting on joint work with Hélène Esnault. In this talk I will outline the basic properties of a newly introduced class of singularities for varieties in positive characteristic, called Wittrational singularites. I will attempt to explain how this notion naturally arises in the context of generalizing results on congruences of rational points of a smooth variety over a finite field beyond the smooth case. In fact, our main result roughtly states that a Wittrational and rationally connected variety has a rational point. Examples of (non) Wittrational varieties will be discussed as well as the relation of Wittrational to a Hodgetheoretic consequence of rational singularities in characteristic zero. 



Jun 6  Tue  Bertrand Toen (Toulouse)  GATA Seminar  
15:00  Stacks and derived categories I  
Hicks Seminar Room J11  
Abstract: The purpose of these two talks is to report on recent works which use stack theory to study derived categories. In the first talk I will discuss the problem of constructing a reasonable moduli space for compact objects in a given triangulated category (or rather a triangulated ``dgcategory''). In a first part I will explain some motivations coming from algebraic geometry and representation theory (e.g. the contruction of moduli spaces of complexes of sheaves on an algebraic variety, the definition of ``Hall algebras'' for derived categories). The second part of the talk will be devoted to present a solution to this problem using a notion of ``derived $\infty$stack'': the main theorem states that the (derived $\infty$) stack of compact objects in a given ``saturated'' dgcategory is algebraic. Some corollaries and possible future applications will be discussed. 



Jun 7  Wed  Bertrand Toen (Toulouse)  GATA Seminar  
15:00  Stacks and derived categories II  
Hicks Seminar Room J11  
Abstract: The second talk is concerned with the problem of constructing a reasonable moduli space for triangulated (dg)categories themselves. The main theorem of this second talk states that the (derived $\infty$) stack of ``saturated dgcategories'' is algebraic. The infinitesimal theory of this moduli stack can be used to explain the relation between the deformation theory of dgcategories and Hochschild cohomology. Two other applications will be discussed. To start with I will describe, for any given rational number p/q, a circle action on the moduli stack of saturated dgcategories whose fixed points are ``CalabiYau dgcategories of dimension p/q''. This can be used to prove that the deformation theory of CalabiYau dgcategories is controlled by cyclic cohomology. Finally, I will explain how the ``period map'', from the stack of varieties to the stack of saturated dgcategories, can be used to study derived equivalence classes of algebraic varieties. 



Jun 14  Wed  Dr Leon Ofman (NASA, USA)  Applied Mathematics Colloquium  
Waves in coronal active regions: observations and models  


Sep 27  Wed  Christian Elsholtz (Royal Holloway)  Pure Maths Colloquium  
16:00  Combinatorial prime number theory  
Hicks Seminar Room J11  
Abstract: In this talk we study combinatorial questions about primes. In particular, Ostmann asked whether there exist two sets A and B (with at least two elements each) so that their sumset A+B equals the set of primes, for sufficiently large primes. Using a new version of the large sieve method we show, that such sets A and B would need to have counting functions of size $N^{1/2 +o(1)}$, whereas previously only a lower bound of $N^{o(1)}$ and an upper bound of $N^{1+o(1)}$ was known. This implies, for example, that the set of primes cannot be decomposed into three such sets. This talk will give a nontechnical survey of the underlying ideas and show how a new type of the large sieve method and combinatorial counting arguments (including graph theory) can be applied to such problems. Other recent work on primes by Green, Tao, Goldston, Pintz and Yildirim will be mentioned 



Oct 4  Wed  Prof. Valentina Zharkova (Bradford)  Applied Mathematics Colloquium  
On the origin of three seismic sources in the 28 October 2003 flare  


Oct 5  Thu  John Fry (Sheffield)  Statistics Seminar  
14:00  The Mathematics of Financial Crashes  


Oct 5  Thu  Keith Harris (Sheffield)  Statistics Seminar  
14:00  Statistical Modelling and Inference for RadioTracking.  


Oct 5  Thu  Holger Brenner (Sheffield)  Topology Seminar  
15:10  Continuous solutions to algebraic forcing equations  
Hicks Seminar Room J11  
Abstract: Let $f_1$, ..., $f_n$ and $f$ be polynomials in $C[X_1,...,X_m]$. When is it possible to write $f = q_1f_1 + ... + q_nf_n$ with continuous functions $q_i: C^m \to C$ ($C$=complex numbers). Does there exists an algebraic characterization of this property? The set of polynomials $f$ which can be written in this way form an ideal which we call the continuous closure of $(f_1,...,f_n)$. We give exclusion and inclusion criteria for this closure operation and algebraic apporoximations, in particular in terms of the axes closure (to be introduced). In the case of a monomial ideal we show that the continuous closure and the axes closure have the same combinatorial description and coincide. 



Oct 10  Tue  Burt Totaro (Cambridge)  Topology Seminar  
14:00  The geometry of Hilbert's fourteenth problem  
Hicks Seminar Room J11  
Abstract: All kinds of classification problems in geometry (going back to Euclid) lead to the problem of finding the ring of polynomial invariant functions for a group acting on a vector space. Hilbert asked whether rings of invariants are always finitely generated. The answer is yes in many cases but no in general, by Nagata. Although the problem is formulated algebraically, Nagata's counterexamples make brilliant use of the geometry of algebraic curves. I will present the latest advances on the problem. 



Oct 11  Wed  Andy Tonks (London Metropolitan University)  Pure Maths Colloquium  
16:00  On $K_1$ (and $K_0$) of a Waldhausen category  
Hicks Seminar Room J11  


Oct 12  Thu  David Jordan (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Poisson brackets on $\mathbb{C}[x,y,z]$  
Hicks Seminar Room J11  
Abstract: The talk will offer various elementary observations on Poisson brackets on $A:=\mathbb{C}[x,y,z]$. Apparently it is of interest to (some) physicists to know when the sum of two Poisson brackets is again a Poisson bracket, in which case the two are said to be compatible. We consider two types of Poisson brackets on $A$, one (which I call exact) depending on one polynomial $F\in A$ and the other (proximate) depending on two such polynomials $G$ and $H$. Here proximate with $H=1$ is exact. The criterion for one exact and one proximate bracket to be compatible turns out to be symmetric in $F, G, H$. Hopefully someone in the audience will point out why this is geometrically obvious! I will then consider how close sums of these compatible pairs come to giving all Poisson brackets on $A$, referring to an existing classification of quadratic Poisson brackets on $A$. Maybe there will be a vague conjecture. Time permitting, I will look at Poisson brackets that restrict to the zero bracket on $B:=\mathbb{C}[x,y]$ and their connection with simple rings of formal differential operators on $B$. 



Oct 18  Wed  Prof Dugald Duncan (HeriotWatt)  Applied Mathematics Colloquium  
Numerical analysis of a convolution model of phase separation  


Oct 18  Wed  Alexey Bondal (Steklov Mathematics Institute)  Pure Maths Colloquium  
16:00  Noncommutative deformations of algebraic varieties and Poisson brackets.  
Hicks Seminar Room J11  
Abstract: The first part of the talk will be a short survey on possible approaches to and results on noncommutative deformations of algebraic verieties, in particular, projective spaces. In the second part we will discuss results and conjectures on the geometric structure of Poisson brackets on Fano varieties. 



Oct 19  Thu  Neil Dummigan (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Euler and the zeta function  
Hicks Seminar Room J11  


Oct 19  Thu  Andrew Stacey (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  A Plethora of Plethories  Describing Unstable Cohomology Operations  
Lecture Theatre 7  
Abstract: Generalised cohomology theories are a useful tool that allow topologists to use algebraic techniques to study topological spaces. One of the bits of baggage that comes with a generalised cohomology theory is the set of operations on said theory. There are several different ways of describing the algebraic structure of a set of operations which vary from the "neat" to the "useful" via the "completely bizarre"; most are described in a paper by Boardman, Johnson, and Wilson in the Handbook of Algebraic Topology. I shall explain some of these descriptions and introduce another one which appears not to have been considered in this context. It uses the notion of a "plethory", which was originally defined (though not by that name) in the 70s by Tall and Wraith. 



Oct 25  Wed  Dr Rony Keppens (K.U.Leuven)  Applied Mathematics Colloquium  
Gridadaptive approaches for computing magnetized plasma dynamics  


Oct 25  Wed  John Power (University of Edinburgh)  Pure Maths Colloquium  
16:00  The Algebra of Computational Effects  
Hicks Seminar Room J11  
Abstract: Lawvere theories and monads have been the two main category theoretic formulations of universal algebra, Lawvere theories arising in 1963 and the connection with monads being established a few years later. Monads, although mathematically the less direct and less malleable formulation, rapidly gained precedence. A generation later, Eugenio Moggi instigated the use monads in theoretical computer science in order to model computational effects, without reference to universal algebra. But since then, the relevance of universal algebra to computational effects has been recognised, leading to renewed prominence of the notion of Lawvere theory, now in a computational setting. Here, we investigate the history, in particular asking why Lawvere theories were eclipsed by monads in the 1960's, and how the renewed interest in them in a computer science setting has been developing and might continue to develop in future. 



Oct 26  Thu  Nikita Markarian (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Nonabelian Hodge theory in characteristic 0 and p>0"  
Hicks Seminar Room J11  
Abstract: We shall give a short review of the nonabelian Hodge theory as it was introduces in works of Deligne, Simpson and others. Then we shall discuss a possible analog of it (for curves) in positive characteristic. 



Oct 31  Tue  Victor Snaith (Sheffield)  Topology Seminar  
14:00  Upper Triangle Technology and the Arf Invariant  
Hicks Seminar Room J11  


Nov 1  Wed  Dr John Barrett (Nottingham)  Applied Mathematics Colloquium  
Geometry of the standard model and neutrino mass terms  


Nov 1  Wed  Paul Turner (HeriotWatt)  Pure Maths Colloquium  
16:00  Khovanov homology for links  
Hicks Seminar Room J11  
Abstract: Khovanov homology is a vector space valued invariant of links whose graded Euler characteristic is the Jones polynomial. It is a stronger invariant than the Jones polynomial, reveals interesting further structure and has nice functorial properties with respect to link cobordisms. In this talk I will endeavour to give an overview of the subject discussing definitions, elementary properties and some applications. 



Nov 2  Thu  Nancy Nicholls (Reading)  Statistics Seminar  
14:00  Getting Started: Data Assimilation for Very Large Inverse Problems in Environmental Science  


Nov 2  Thu  David Stern (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Exceptional collections and mutations on Del Pezzo surfaces.  
Hicks Seminar Room J11  
Abstract: Abstract: This talk will use special collections of bundles to obtain abelian categories that are derived equivalent to the category of coherent sheaves of a Del Pezzo surface. These abelian categories are the categories of modules of the homomorphism algebra of bundles in the collection which can be described as the path algebra of a quiver. These constructions work on strong exceptional collections and the main focus of the talk will be to describe an operation, called mutation, acting on a closed set of such collections. 



Nov 7  Tue  Alastair Craw (Glasgow)  Topology Seminar  
14:00  
Hicks Seminar Room J11  


Nov 8  Wed  Dr Yasmin Andrew (JET (Culham))  Applied Mathematics Colloquium  
Experimental Studies of the LH Transition on JET  


Nov 8  Wed  Alastair Craw (University of Glasgow)  Pure Maths Colloquium  
16:00  
Hicks Seminar Room J11  


Nov 9  Thu  Clive Anderson (Sheffield)  Statistics Seminar  
14:00  Some Extreme Value Problems in Metal Fatigue  


Nov 13  Mon  Mikhail Kapranov (Yale University)  GATA Seminar  
14:00  Talk 1: "Spaces of formal loops and gerbes of chiral differential operators"  
Hicks Seminar Room J11  
Abstract: For a complex manifold X physics considerations lead to a construction of certain sheaves of vertex algebras on X called chiral differential operators (CDO). While locally such a sheaf is unique, globally the situation is similar to that of spinor bundles on a Riemannian manifold. In the categorical terminology they form a gerbe. We relate this gerbe with the gerbe describing 'determinantal anomaly' for the space of free loops in X. The calculation of the class of the gerbe of CDO due to Gorbounov, Malikov and Schechtman turns out to be a particular case of a local RiemannRochtype theorem for determinantal gerbes. 



Nov 14  Tue  Neil Strickland (Sheffield)  Topology Seminar  
14:00  Structured ring spectra and the nilpotence theorem  
Hicks Seminar Room J11  
Abstract: One form of the nilpotence theorem says that if $R$ is a ring spectrum and $a\in\pi_dR$ maps to zero in $MU_dR$ then $a^n=0$ for large $n$. This is a very powerful result, which forms the basis for a huge body of work in stable homotopy theory. Strangely, however, little further work has been done with the circle of ideas used in the proof of the nilpotence theorem. In this talk we will revisit these ideas using some newer technology of structured ring spectra. 



Nov 15  Wed  Dr Konstantin Ilin (York)  Applied Mathematics Colloquium  
The stability of tangential and rotational discontinuities in MHD  


Nov 15  Wed  Peter Jorgensen (Newcastle)  Pure Maths Colloquium  
16:00  Interactions between algebra, analysis, and topology  
Hicks Seminar Room J11  


Nov 16  Thu  David Scott (Auckland)  Statistics Seminar  
14:00  The hyperbolic and related distributions: problems of implementation  


Nov 16  Thu  Mikhail Kapranov (Yale University)  GATA Seminar  
15:10  Talk 2: "Spaces of formal loops and gerbes of chiral differential operators."  
Hicks Seminar Room J11  
Abstract: For a complex manifold X physics considerations lead to a construction of certain sheaves of vertex algebras on X called chiral differential operators (CDO). While locally such a sheaf is unique, globally the situation is similar to that of spinor bundles on a Riemannian manifold. In the categorical terminology they form a gerbe. We relate this gerbe with the gerbe describing 'determinantal anomaly' for the space of free loops in X. The calculation of the class of the gerbe of CDO due to Gorbounov, Malikov and Schechtman turns out to be a particular case of a local RiemannRochtype theorem for determinantal gerbes. 



Nov 21  Tue  Mikhail Kapranov (Yale University)  GATA Seminar  
14:00  Talk 3: "Spaces of formal loops and gerbes of chiral differential operators."  
Hicks Seminar Room J11  
Abstract: For a complex manifold X physics considerations lead to a construction of certain sheaves of vertex algebras on X called chiral differential operators (CDO). While locally such a sheaf is unique, globally the situation is similar to that of spinor bundles on a Riemannian manifold. In the categorical terminology they form a gerbe. We relate this gerbe with the gerbe describing 'determinantal anomaly' for the space of free loops in X. The calculation of the class of the gerbe of CDO due to Gorbounov, Malikov and Schechtman turns out to be a particular case of a local RiemannRochtype theorem for determinantal gerbes. 



Nov 22  Wed  Dr Lisa Hall (Sheffield)  Applied Mathematics Colloquium  
Consistent modified gravity models  


Nov 22  Wed  Samir Siksek (University of Warwick)  Pure Maths Colloquium  
16:00  Classical Diophantine Equations and the Proof of Fermat's Last Theorem  
Hicks Seminar Room J11  
Abstract: Wiles' proof of Fermat's Last Theorem is one of the happiest memories of the 20th century. Unfortunately, Wiles' proof does not readily extend in a way that allows us to solve many other classical Diophantine problems. In this talk, based on joint work with Bugeaud and Mignotte, we explain how the proof of Fermat's Last Theorem can be combined with older analytic techniques due to Baker, in a way that solves several classical Diophantine problems. For example, we show that the only perfect powers in the Fibonacci sequences are 0, 1, 8, 144. 



Nov 23  Thu  Stuart Barber (Leeds)  Statistics Seminar  
14:00  Signal processing using complex Daubechies wavelets  


Nov 23  Thu  Konstantin Ardakov (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Iwasawa algebras  
Hicks Seminar Room J11  


Nov 29  Wed  Dr Duncan Mackay (St. Andrews)  Applied Mathematics Colloquium  
MHD Simulations of Solar Prominences  


Nov 29  Wed  Herbert Gangl (University of Durham)  Pure Maths Colloquium  
16:00  Multiple polylogarithms, polygons and algebraic cycles.  
Hicks Seminar Room J11  


Nov 30  Thu  David Barnes (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  Categories with Involution  
Hicks Seminar Room J11  


Nov 30  Thu  Goran Peskir (Manchester)  Statistics Seminar  
14:00  Optimal stopping  


Nov 30  Thu  Konstantin Ardakov (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Iwasawa algebras II  
Hicks Seminar Room J11  


Dec 5  Tue  Andrew Ranicki (Edinburgh)  Topology Seminar  
14:00  The geometric Hopf invariant  
Hicks Seminar Room J11  
Abstract: The talk will be a report on an ongoing joint project with Michael Crabb (Aberdeen). The geometric Hopf invariant of a stable map $F:\Sigma^{\infty}X \to \Sigma^{\infty}Y$ is a stable $Z_2$equivariant map $h(F):X \to (S^{\infty})^+\wedge(Y \wedge Y)$ to the quadratic construction on $Y$. The stable $Z_2$equivariant homotopy class of $h(F)$ is the primary obstruction to desuspending $F$. The geometric Hopf invariant of the stable Umkehr map $F:\Sigma^{\infty}M^+ \to \Sigma^{\infty}T(\nu_f)$ of an immersion $f:N^n\to M^m$ of manifolds factors through the $Z_2$equivariant double point set of $f$. The $\pi_1$equivariant version of the geometric Hopf invariant has an application to Wall's nonsimplyconnected surgery theory. 



Dec 6  Wed  Toby Stafford (University of Michigan)  Pure Maths Colloquium  
16:00  Noncommutative Projective Surfaces  
Hicks Seminar Room J11  
Abstract: Noncommutative projective geometry seeks to use the intuition and techniques from classical projective algebraic geometry to understand the structure of noncommutative algebras and related modules categories. In this talk I will survey some of the basic ideas and techniques in the subject and, time permitting, outline recent work that describes a large class of ``noncommutative surfaces'' which have some weird and wonderful properties. 



Dec 7  Thu  Raj Bhansali (Liverpool)  Statistics Seminar  
14:00  Frequency Analysis of Chaotic Intermittency Maps with Slowly Decaying Correlations  


Dec 12  Tue  Simon Willerton (Sheffield)  Topology Seminar  
14:00  Hopf Monads  
Hicks Seminar Room J11  
Abstract: Representations of finite groups have various nice properties, you can tensor two representations together to get another representation and you can take the dual of a representation to get a new representation. This makes the category of representations into a `monoidal category with duals' which lifts these structures from the category of vector spaces. More generally this is true of the representations of any Hopf algebra. A monad is a categorical gadget which can be viewed as generalization of an algebra (in a sense I will explain), and which has a category of representations. Motivated by some specific examples you can ask when the category of representations is a monoidal category with duals (ie when the monad is a *Hopf* monad). I will endeavour to explain my pictorial approach to the answer given by Bruguiere and Virilizier. 



Dec 13  Wed  Prof Koji Ohkitani (Sheffield)  Applied Mathematics Colloquium  
Blowup and regularity problems of hypoviscous fluid equations.  


Dec 13  Wed  Paul Smith (University of Washington)  Pure Maths Colloquium  
16:00  Noncommutative Hirzebruch surfaces  
Hicks Seminar Room J11  
Abstract: I will introduce the audience to some of the main ideas and methods in noncommutative algebraic geometry by focusing on a rich class of examples, the spaces of the title, and showing how closely their behavior follows that in the commutative case. Our results about noncommutative Hirzebruch surfaces, $qF_n$, specialize to the commutative case: for example, there is a map, in the sense of noncommutative geometry, to the projective line, there is a curve on $qF_n$ with selfintersection number (defined in terms of the Euler form on the Grothendieck group) $n$, and contracting that curves provides maps to other wellknown noncommutative surfaces that are again analogues of their commutative counterparts. The starting point for the definition and analysis is a noncommutative analogue of Cox's homogeneous coordinate ring of a toric variety. 



Dec 14  Thu  Stefanie Biedermann (Southampton)  Statistics Seminar  
14:00  Robust optimal designs for doseresponse experiments  


Dec 14  Thu  Sukhendu Mehrotra (Sheffield)  Algebra / Algebraic Geometry seminar  
15:10  Stability Manifolds as Extended Kaehler Moduli Spaces  
Hicks Seminar Room J11  


Jan 15  Mon  Sarah Whitehouse (Sheffield)  Chromatic homotopy  
14:00  Topological Hochschild Homology  
Hicks Seminar Room J11  


Feb 7  Wed  Jitesh S.B. Gajjar (Manchester)  Applied Mathematics Colloquium  
16:00  Global stability calculations of some separated flows  


Feb 7  Wed  Kevin Buzzard (Imperial College London)  Pure Maths Colloquium  
16:15  Artin's conjecture on Lfunctions  
Hicks Seminar Room J11  


Feb 8  Thu  Elke Thonnes (University of Warwick)  Statistics Seminar  
14:00  Statistical analysis of pore patterns in fingerprints  


Feb 14  Wed  Ivan Fesenko (Nottingham)  Pure Maths Colloquium  
16:00  Dealing with noncommutative aspects of 1d number theory in a commutative 2d way  
Hicks Seminar Room J11  


Feb 14  Wed  Rich Kerswell (Bristol)  Applied Mathematics Colloquium  
16:00  Transition to Turbulence in a Pipe  


Feb 16  Fri  Neil Dummigan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  padic Hodge theory I  
Hicks Seminar Room J11  
Abstract: Global and local Galois groups, Frobenius elements, cyclotomic characters, Tate modules of elliptic curves. 



Feb 20  Tue  John Greenlees (Sheffield)  Topology Seminar  
14:00  Rational cohomology theories on free $G$spaces  
Hicks Seminar Room J11  
Abstract: I aim to describe a classification for the theories of the title. More precisely, they are classified by free rational $G$spectra, and I will describe an algebraic model when $G$ is a connected compact Lie group (the category of torsion modules over the polynomial ring $H^*(BG;Q)$). The two ingredients are an Adams spectral sequence and derived Morita theory. (Joint work with Brooke Shipley). 



Feb 21  Wed  Silvia Dalla (Manchester)  Applied Mathematics Colloquium  
16:00  Solar science with AstroGrid  


Feb 22  Thu  Almar Kaid  Pure Maths Postgraduate Seminar  
12:10  Detecting semistability of vector bundles on curves  
Hicks Seminar Room J11  


Feb 22  Thu  Ed Cripps (Sheffield)  Statistics Seminar  
14:00  Variable selection and covariance selection in multivariate Gaussian linear regression  


Feb 27  Tue  John Greenlees (Sheffield)  Topology Seminar  
14:00  Rational cohomology theories on free $G$spaces pt II  
Hicks Seminar Room J11  
Abstract: I aim to describe a classification for the theories of the title. More precisely, they are classified by free rational $G$spectra, and I will describe an algebraic model when $G$ is a connected compact Lie group (the category of torsion modules over the polynomial ring $H^*(BG;Q)$). The two ingredients are an Adams spectral sequence and derived Morita theory. (Joint work with Brooke Shipley). 



Feb 28  Wed  Tony Arber (Warwick)  Applied Mathematics Colloquium  
16:00  Emergence of flux through into the Solar corona: the effect of partially ionized layers  


Feb 28  Wed  Meinolf Geck (Aberdeen)  Pure Maths Colloquium  
16:15  Representations of Hecke algebras  
Hicks Seminar Room J11  
Abstract: Hecke algebras arise in various contexts in Mathematics, ranging from knot theory (construction of the famous Jones polynomial) to the theory of finite groups. They possess a rich and involved combinatorial structure. The purpose of the talk is to explain the role that these algebras play in the representation theory of finite groups and to highlight some recent advances. 



Mar 2  Fri  Neil Dummigan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  padic Hodge theory II  
Hicks Seminar Room J11  
Abstract: Big rings, comparison theorems, de Rham and crystalline representations. 



Mar 5  Mon  Jos (Universidad Nacional Aut)  Topology Seminar  
14:00  Characteristic Classes and Transversality  
Hicks Seminar Room J11  
Abstract: Let $\xi$ be a smooth vector bundle over a differentiable manifold $M$. Let $h : \epsilon^{ni+1}\to \xi$ be a generic bundle morphism from the trivial bundle of rank $ni+1$ to $\xi$. We give a geometric construction of the StiefelWhitney classes when $\xi$ is a real vector bundle, and of the Chern classes when $\xi$ is a complex vector bundle. Using $h$ we define a differentiable closed manifold $Z(h)$ and a map $\phi : Z(h)\to M$ whose image is the singular set of $h$. The $i$th characteristic class of $\xi$ is the Poincaré dual of the image, under the homomorphism induced in homology by $\phi$, of the fundamental class of the manifold $Z(h)$. We extend this definition for vector bundles over a paracompact space, using that the universal bundle is filtered by smooth vector bundles. 



Mar 6  Tue  Martin Crossley (Swansea)  Topology Seminar  
14:00  Word Hopf Algebras  
Hicks Seminar Room J11  
Abstract: Hopf algebras of words appear in many contexts, particularly in topology and in combinatorics. I'll discuss a few of these situations a number of results both old, new, false and true about them. 



Mar 7  Wed  T. Talipova (Institute of Applied Physics, Russian Academy of Sciences)  Applied Mathematics Colloquium  
16:00  The Gardner equation in nonlinear theory of wave motion in stratified medium  


Mar 7  Wed  Elmer Rees (Bristol)  Pure Maths Colloquium  
16:15  Frobenius's higher characters and some more recent developments  
Hicks Seminar Room J11  


Mar 9  Fri  Neil Dummigan (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  padic Hodge theory III  
Hicks Seminar Room J11  


Mar 13  Tue  Richard Hepworth (Sheffield)  Topology Seminar  
14:00  ChenRuan Cohomology  
Hicks Seminar Room J11  
Abstract: ChenRuan cohomology seems to be the correct notion of cohomology for orbifolds. Sadly, the definition is rather complicated since it involves differential operators on Riemann surfaces. I will motivate and define orbifolds and ChenRuan cohomology before explaining how all of the complications can be reduced to a single property of the socalled age grading. 



Mar 14  Wed  Andrew Booker (Bristol)  Pure Maths Colloquium  
16:00  New twists on an old idea of Turing  
Hicks Seminar Room J11  


Mar 16  Fri  Frazer Jarvis (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Introduction to group schemes  
Hicks Seminar Room J11  


Mar 20  Tue  Julia Singer (Bonn)  Topology Seminar  
14:00  Equivariant Lambda Rings  
Hicks Seminar Room J11  
Abstract: The existence of commutative multiplications on Moore spectra for certain types of rings leads to algebraic conditions providing additional structure on the rings. I'll explain why this can be thought of as an equivariant generalisation of a lambda ring structure. 



Mar 21  Wed  MayWin Thein (New Hampshire)  Applied Mathematics Colloquium  
16:00  Celestial Navigation (CelNav): Lunar Surface Navigation  


Mar 21  Wed  Harold Stark (California, San Diego)  Pure Maths Colloquium  
16:15  The Gauss ClassNumber Problems  
Hicks Seminar Room J11  


Mar 22  Thu  Panagiotis Tsaknias (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  "Constructing Galois representations from modular forms"  
Hicks Seminar Room J11  


Mar 22  Thu  SÃ¸ren Asmussen (Aarhus)  Statistics Seminar  
14:00  Tail Probabilities for a Computer Reliability Problem  


Mar 23  Fri  Frazer Jarvis (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  To be announced  
Hicks Seminar Room J11  


Apr 18  Wed  Jonathan Pila (Bristol)  Pure Maths Colloquium  
16:00  Density of rational points  
Hicks Seminar Room J11  
Abstract: The basic questions of diophantine geometry concern rational or integral points on an algebraic variety: do they exist, how can they be described (or found), how are they distributed, etc. Such questions lead to deep theorems (often ineffective in various ways) and farreaching conjectures. This talk will be about a circle of problems and results on giving simply upper bound estimates for the number of integer or rational points up to a given height. I will describe a quite elementary method that yields results that, while relatively weak for an individual variety, are uniform over large classes of varieties. This uniformity has made the results useful. The same methods are also applicable to certain nonalgebraic sets. I will describe a result about rational points on the graph of a transcendental realanalytic function and a connection with transcendence theory. I will finally describe a result on the rational points of analytic (and more general) sets of arbitrary dimension and further connections with transcendence theory. 



Apr 18  Wed  Patrick Fowler (Sheffield (Chemistry Department))  Applied Mathematics Colloquium  
16:00  Mapping currents in molecules  


Apr 25  Wed  Christian Boehmer (Portsmouth)  Applied Mathematics Colloquium  
16:00  Does the cosmological constant imply the existence of a minimal energy density?  


Apr 27  Fri  Jayanta Manoharmayum (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Deformations of Galois representations  
Hicks Seminar Room J11  


Apr 30  Mon  Constanze Roitzheim (Sheffield)  Chromatic homotopy  
13:00  Hopf Invariant One for Odd Primes  
Hicks Seminar Room J11  


May 2  Wed  Tom Van Doorsselaere (Warwick)  Applied Mathematics Colloquium  
15:00  Recent results in coronal loop seismology: determination of the nonideal damping mechanism and the density scale height  


May 2  Wed  Simon Wadsley (Cambridge)  Pure Maths Colloquium  
16:00  $K_0$ of ptorsion modules for Iwasawa algebras  
Hicks Seminar Room J11  


May 3  Thu  Harry Ullman (Sheffield)  Pure Maths Postgraduate Seminar  
12:10  The Stable Splitting of $U(n)$  
Hicks Seminar Room J11  


May 3  Thu  Chris Williams (Edinburgh)  Statistics Seminar  
14:00  Gaussian processes and machine learning  


May 4  Fri  Jayanta Manoharmayum (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Deformations of Galois representations II  
Hicks Seminar Room J11  


May 8  Tue  Ruben Sanchez (Sheffield)  Topology Seminar  
14:00  Computing Borel's regulator  
Hicks Seminar Room J11  
Abstract: The Borel's regulator map is a useful tool to study the higher algebraic Ktheory of the ring of integers of an algebraic number field. In 2000, Hamida proved a formula for the Borel's regulator as an integral of noncommutative differential forms. We will present a formula to approximate this integral which can lead to explicit computations. Finally, we will discuss a padic version of this. 



May 9  Wed  Jerome Scherer (UAB Barcelona)  Pure Maths Colloquium  
16:00  
Hicks Seminar Room J11  


May 9  Wed  Sergei Nazarenko (Warwick)  Applied Mathematics Colloquium  
16:00  Leithtype model of 2D turbulence and its predictions  


May 10  Thu  Simon TavarÃ© (Southern California)  Statistics Seminar  
14:00  Stochastic processes in stem cell evolution  


May 11  Fri  Cristina Lopez Martin (University of Salamanca (visiting Warwick))  Algebra / Algebraic Geometry seminar  
14:10  FourierMukai transforms and moduli spaces of sheaves on elliptic curves  
Hicks Seminar Room J11  


May 15  Tue  Richard Hepworth (Sheffield)  Topology Seminar  
14:00  What is a KO object?  
Hicks Seminar Room J11  
Abstract: The real question is "What is an elliptic object?". Stolz and Teichner have been trying to answer this, and along the way they have developed a new perspective on Ktheory. In this expository talk I'll try to explain a little bit of this, hopefully ending with a sketch of StolzTeichner's theorem describing the KOtheory spectrum in terms of euclidean field theories. 



May 16  Wed  Jacek Brodzki (Southampton)  Pure Maths Colloquium  
16:00  Why can't metric spaces be more like groups?  
Lecture Theatre 2  
Abstract: Research into the BaumConnes conjecture and related issues provides examples of nontrivial and fruitful interactions between analysis and geometry of (among others) discrete groups. On the other hand, ideas of Gromov, Roe and others gave rise to a programme of large scale geometry, where two objects are declared equivalent if they "look the same" from a distance. In this talk I shall describe new ideas and results that arise from efforts to unify certain features of both programmes. 



May 16  Wed  Roddy Vann (York)  Applied Mathematics Colloquium  
16:00  A burning fusion plasma: theoretical challenges  


May 18  Fri  Helena FischbacherWeitz (University of Southampton)  Algebra / Algebraic Geometry seminar  
14:10  An equivariant RiemannRoch theorem for curves  
Hicks Seminar Room J11  
Abstract: Let $X$ be an algebraic curve over a field $k$, let $D$ be a divisor on $X$, and let $\mathcal{O}_X(D)$ denote the invertible sheaf (or line bundle) associated to D on X. We are interested in the 0th cohomology group $H^0(X,\mathcal{O}_X(D))$ of this sheaf, which can be viewed a space of functions on X whose pole and zero orders are bounded by the values of D. Its dimension as a kvector space is computed by the ``classical'' RiemannRoch theorem: $$ \dim H^0(X, \mathcal{O}_X(D))  \dim H^1(X, L(D))= deg D + 1  g,$$ where $g$ is the genus of $X$. If we now consider the action of a finite group $G$ on $X$, and if we require $D$ to be $G$stable, then $G$ also acts on the cohomology groups of $\mathcal{O}_X(D)$, and we have RiemannRoch type theorems which compute the equivariant Euler characteristic $$ [H^0(X, \mathcal{O}_X(D))]  [H^1(X,\mathcal{O}_X(D))]$$ as an element of the Grothendieck group of $k[G]$modules, and further in the Grothendieck group of projective $k[G]$modules. The emphasis in this talk will be on the case where the underlying field $k$ is perfect, but not necessarily algebraically closed. 



May 21  Mon  Tore Kro (NTNU)  Topology Seminar  
14:00  Geometry of elliptic cohomology  
Hicks Seminar Room J11  
Abstract: We review what elliptic cohomology is. Furthermore, we will mention the various attempts to define it geometrically. In the program initiated by Baas, the idea is to consider 2vector bundles. We will look at their definition, and the related notion of charted 2bundles, and give examples. 



May 22  Tue  Tore Kro (NTNU)  Topology Seminar  
14:00  What does the nerve of a 2category classify?  
Hicks Seminar Room J11  
Abstract: We outline the proof showing that the nerve of a topological 2category classifies charted 2bundles structured by this 2category. As a corollary, we will see that the Ktheory associated to Baez and Crans 2vector bundles splits as two copies of ordinary Ktheory. 



May 22  Tue  Andrei Caldararu (Wisconsin)  GATA Seminar  
15:45  The Mukai pairing on Hochschild homology  
Hicks Seminar Room J11  
Abstract: Given a CalabiYau threefold X, string theory constructs two socalled topological twists, the Amodel and the Bmodel. A piece of the mathematical incarnation of the Amodel is the singular cohomology ring of X (or its quantum deformation). The corresponding piece in the Bmodel is encoded by the Hochschild cohomology ring of X. Physics predicts both sets of data are Frobenius algebras, i.e., they are endowed with a nondegenerate pairing. In the Amodel, this is given by the Poincare pairing on cohomology. In my talk I shall discuss the construction of the corresponding pairing on Hochschild (co)homology. I shall also discuss several important properties of this pairing, including the Cardy condition from openclosed topological string theory. 



May 23  Wed  Johan Anderson (Sheffield)  Applied Mathematics Colloquium  
16:00  Comparison of theoretical models to zonal flow generation and the effects of backreaction of zonal flows on ITG turbulence  


May 23  Wed  Andrei Caldararu (Wisconsin)  GATA Seminar  
16:00  The PfaffianGrassmannian derived equivalence  
Hicks Seminar Room J11  
Abstract: We argue that there exists a derived equivalence between CalabiYau threefolds obtained by taking hyperplane sections (of the appropriate codimension) of the Grassmannian G(2,7) and the Pfaffian Pf(7). The existence of such an equivalence has been conjectured by physicists for almost ten years, as the two families of CalabiYau threefolds are believed to have the same mirror. It is the first example of a derived equivalence between CalabiYau threefolds which are provably nonbirational. 



May 25  Fri  Jonathan Elmer (University of Kent)  Algebra / Algebraic Geometry seminar  
14:10  Modular Invariant Rings of Minimal Depth  
Hicks Seminar Room J11  
Abstract: Let G be a finite group, V a kGmodule over a field k of characteristic p, and R:=S(V^*), and let R^G be the corresponding ring of invariants. It is well known that if p does not divide G, then R^G is a CohenMacaulay ring. Equivalently, depth(R^G) = dim(R^G), or "R^G has maximal depth". Little is known in general about the depth of modular invariant rings in general, although thanks to Ellingsrud and Skjelbred we do have a lower bound for depth(R^G). A representation V for which this lower bound is attained is called "flat". In this talk we introduce a slightly narrower class of representations (called "strongly flat") and show that although not all flat representations are strongly flat, this notion is sufficiently general to produce a wealth of new examples of flat representations. 



May 29  Tue  Ieke Moerdijk (Sheffield)  Topology Seminar  
14:00  To what extent is Lie theory for groupoids like that for groups?  
Hicks Seminar Room J11  
Abstract: Lie groupoids play an increasingly important role in foliation theory, symplectic and Poisson geometry, and noncommutative geometry. In this lecture, we explain how some basic properties of Lie groups extend to groupoids, and how some other properties don't. The talk will only presuppose some basic familiarity with Lie groups, and in particular should be understandable to the students who attended my recent RTP course. 



May 30  Wed  Ruben Sanchez (Sheffield)  Topology Seminar  
16:00  Computing Borel's regulator II  
Hicks Seminar Room J11  
Abstract: The Borel's regulator map is a useful tool to study the higher algebraic Ktheory of the ring of integers of an algebraic number field. In 2000, Hamida proved a formula for the Borel's regulator as an integral of noncommutative differential forms. We will present a formula to approximate this integral which can lead to explicit computations. Note: This talk is independent of the first one except some knowledge of algebraic Ktheory and motivation. 



May 30  Wed  Daniel Brown (Aberystwyth)  Applied Mathematics Colloquium  
16:00  The onset of xray bright points in the solar corona  


May 31  Thu  Mark Davis (Imperial)  Statistics Seminar  
14:00  


Jun 6  Wed  Shunsuke Takagi (Fukuoka)  
13:30  Finiteness properties of rings with finite Frepresentation type  
Hicks Seminar Room J11  


Jun 6  Wed  Rodney Sharp (Sheffield)  
14:40  Further interactions between graded annihilators and tight closure  
Hicks Seminar Room J11  


Jun 6  Wed  Reza Tavakol (Queen Mary)  Applied Mathematics Colloquium  
16:00  Dynamo models and differential rotation in the Sun and latetype rapidly rotating stars  


Jun 6  Wed  Craig Huneke (University of Kansas)  GATA Seminar  
16:00  How many times does a polynomial vanish at a point? (GATA lecture I)  
Hicks Seminar Room J11  


Jun 7  Thu  Shunsuke Takagi (Fukuoka)  
11:00  Rationality of Fjumping exponents on singular varieties  
Hicks Seminar Room J11  


Jun 7  Thu  Yuji Yoshino (Okayama)  
13:30  Noncommutative parameter algebras of universal liftings of chain complexes  
Hicks Seminar Room J11  


Jun 7  Thu  Holger Brenner (Sheffield)  
14:40  Some challenging examples for the localization problem in tight closure  


Jun 7  Thu  Craig Huneke (University of Kansas)  GATA Seminar  
16:00  Reduction to characteristic p, and further refinements of vanishing along algebraic subsets (GATA lecture II)  
Hicks Seminar Room J11  


Jun 8  Fri  Vladimir Bavula (Sheffield)  
11:00  The Jacobian map, the Jacobian group and the group of automorphisms of the Grassmann algebra  
Hicks Seminar Room J11  


Jun 8  Fri  Yuji Yoshino (Okayama)  
13:30  Local cohomologies with nonclosed supports  
Hicks Seminar Room J11  


Jun 8  Fri  Moty Katzman (Sheffield)  
14:40  Frobenius structures on injective hulls and their applications  
Hicks Seminar Room J11  


Jun 8  Fri  Craig Huneke (University of Kansas)  GATA Seminar  
16:00  Absolute integral closures in mixed characteristic and characteristic p (GATA lecture III)  
Hicks Seminar Room J11  


Sep 25  Tue  Birgit Richter (Hamburg)  
16:00  Ktheory of 2vector spaces  


Sep 26  Wed  Birgit Richter (Hamburg)  
14:00  Ktheory of bipermutative categories I  


Sep 27  Thu  Birgit Richter (Hamburg)  
14:00  Ktheory of bipermutative categories II  


Oct 2  Tue  Eugenia Cheng (Sheffield)  Topology Seminar  
14:00  An operadic approach to $n$categories  
Hicks Seminar Room J11  
Abstract: Operads provide a way of studying loop spaces, by giving a formalism for keeping track of weakly associative multiplication. In this talk I will discuss how this is related to study of weak $n$categories, where now we must keep track of weakly associative composition. I will present the definition of weak $n$category proposed by Trimble, which uses one specific and very straightforward topological operad. This can be generalised so that we can use other operads such as the little intervals operad and possibly many of your favourite loop space operads. 



Oct 3  Wed  Vic Snaith (Sheffield)  Pure Maths Colloquium  
16:30  From Algebraic Cobordism to Algebraic Cobordism in only 31 Years  
Hicks Seminar Room J11  


Oct 4  Thu  Kirill Mackenzie (Sheffield)  
12:10  Lie algebras: integration by paths  
Hicks Seminar Room J11  
Abstract: There are several distinct proofs of the integrability of (finite dimensional, real) Lie algebras, but the main purpose of this seminar is to describe the proof of Duistermaat using path spaces. This method is the foundation of the solution of the integrability problem for Lie algebroids and in retrospect can also be seen as underlying the construction by Cattaneo and Felder of a symplectic realization for any Poisson manifold, using Poisson sigma models. If time and interest are available there will be a second talk on (Poisson) sigma models which I hope will provide some background for Cattaneo's talk in Sheffield on October 24th. 



Oct 5  Fri  David Gepner (Sheffield)  Higher Category Theory  
13:00  Organisational meeting  
Hicks Lecture Room 10  


Oct 5  Fri  Mykola Gordovskyy (Sheffield)  
13:05  
Lecture Theatre 9  


Oct 9  Tue  Paul Mitchener (Sheffield)  Topology Seminar  
14:00  Coarse Geometry  
Hicks Seminar Room J11  
Abstract: Topology arises from the study of continuous maps, and essentially what happens at very small distances. Coarse geometry, by contrast, ignores all local structure, and only examines very large scale details. Essentially, all that matters in coarse geometry is what is going on `at infinity'. In this talk we will introduce the basic notions of coarse geometry, along with a number of examples and coarse invariants that are analogous to standard invariants in algebraic topology. 



Oct 9  Tue  David Applebaum (Sheffield)  
17:00  Some Random Thoughts on the Laplacian  
Hicks Lecture Theatre 7  
Abstract: The Laplacian is one of the most important linear operators in mathematics. One reason for this is its ubiquitous role in important second order partial differential equations (pdes) and this lecture will focus mainly on the heat equation. I'll describe the probabilistic method of solving this pde using Brownian motion and show how this relates to the modern analytical approach via semigroup theory. In the last part of the talk, we'll bring in some geometry and I'll describe how the Laplacian on a compact Riemannian manifold can yield information about the curvature. 



Oct 10  Wed  Tim Dokchitser (Cambridge)  Pure Maths Colloquium  
16:00  Parity Conjecture for elliptic curves  
Hicks Seminar Room J11  


Oct 10  Wed  Dr Matthew P.Juniper (University of Cambridge)  Applied Mathematics Colloquium  
16:00  'Absolute Stability in Fuel Injectors'  
Hicks Lecture Theatre 6  


Oct 11  Thu  Richard Jacques (University of Sheffield)  Statistics Seminar  
14:00  Classification Methods for the Analysis of High Content Screening Data  
Hicks Room K14  
Abstract: The current paradigm for the identification of candidate drugs within the pharmaceutical industry typically involves the use of high throughput screens. A high throughput screen allows a large number of compounds to be tested in a biological assay in order to identify any activity inhibiting or activating a biological process. From each of the assays run through a high throughput screen a high content screen image is produced which can be analysed using advanced imaging algorithms to produce a set of variables which reflect the observed activity of the cells within the image. Classification methods have important applications in the analysis of high content screening data where they are used to predict which compounds have the potential to be developed into new drugs. Statistical approaches have been developed that enable classification using a single parameter. However, approaches for multiparametric selection are still in their infancy. Furthermore, proper exploitation of the information contained within each high content screen image will enable more refined compound selection. A new classification technique for the analysis of data from high content screening experiments will be presented and the methodology illustrated on an example data set using a random forest classifier. 



Oct 11  Thu  Michailina Siakalli (University of Sheffield)  Statistics Seminar  
14:00  Stochastic Stabilization  
Hicks Room K14  
Abstract: In simple words stability of a dynamic system means sensitivity of the system to changes. Consider a first order nonlinear differential equation system dx(t)\dt=f(x(t)). Investigating what happens when noise is added, it has so far been observed that Brownian motion noise can stabilize an unstable system or destabilize it in the case that is stable. In my talk I will describe what is happening when the given nonlinear system is perturbed by different types of Poisson noise. 



Oct 12  Fri  Eugenia Cheng (Sheffield)  Higher Category Theory  
13:00  Introduction  
Hicks Seminar Room J11  


Oct 12  Fri  Johan Anderson (Sheffield)  
13:05  
Lecture Theatre 9  


Oct 12  Fri  Simon Willerton (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Lowdimensional algebra  
Hicks Seminar Room J11  


Oct 15  Mon  Kirill Mackenzie (Sheffield)  
14:30  Integration of Lie algebras, continued  
Hicks Seminar Room J11  


Oct 16  Tue  Teimuraz Pirashvili (Leicester)  Topology Seminar  
14:00  Second Hochschild cohomology and triangulated categories  
Hicks Seminar Room J11  


Oct 17  Wed  David Rydh (Stockholm)  Algebra / Algebraic Geometry seminar  
13:10  Submersions and effective descent of etale morphisms  
Hicks Seminar Room J11  


Oct 17  Wed  Elizabeth Allman (Fairbanks, visiting Newton institute)  Pure Maths Colloquium  
16:00  Models of DNA site substitution  
Hicks Seminar Room J11  
Abstract: Molecular phylogenetics is concerned with inferring evolutionary relationships (phylogenetic trees) from biological sequences (such as aligned DNA sequences for a gene shared by a collection of species). The probabilistic models of sequence evolution that underly statistical approaches in this field exhibit a rich algebraic structure. After an introduction to the inference problem and phylogenetic models, this talk will survey some of the highlights of current algebraic understanding. Results on the important statistical issue of identifiability of phylogenetic models will be emphasized, as the algebraic viewpoint has been crucial to obtaining such results. 



Oct 18  Thu  Steve Buckland (The National Centre for Statistical Ecology)  RSS Seminar  
14:30  Embedding population dynamics models in inference  
Hicks Room K14  
Abstract: Increasing pressures on the environment are generating an everincreasing need to manage animal and plant populations sustainably, and to protect and rebuild endangered populations. Effective management requires reliable mathematical models, so that the consequences of management action can be predicted, and the uncertainty in these predictions quantified. These models must be able to predict the response of populations to anthropogenic change, while handling the major sources of uncertainty. We describe a simple Â'building blockÂ' approach to formulating discretetime models. These models may include demographic stochasticity, environmental variability through covariates or random effects, multispecies dynamics such as in predatorprey and competition models, movement such as in metapopulation models, nonlinear effects such as density dependence, and mating models. We discuss methods for fitting such models to time series of data, and quantifying uncertainty in parameter estimates and population states, including model uncertainty, using computerintensive Bayesian methods. 



Oct 18  Thu  Rachel Borysiewicz (The National Centre for Statistical Ecology)  RSS Seminar  
14:30  Integrated population modelling for multisite data  
Hicks Room K14  
Abstract: The statistical analysis of markrecapturerecovery (MRR) data collected on wild animal populations dates back to the 1960s, when the foundation was laid for stochastic models fitted to data by the method of maximum likelihood. In recent years an active area of research has developed which combines MRR data with census data. The census data can be described by statespace models and the Kalman filter provides a mechanism for forming the census likelihood. Model fitting then follows by maximising a combined likelihood that is the product of component likelihoods. By combining multiple data sources it has been found that as well as increasing precision of common parameters, it is also possible to estimate parameters which would be inestimable from the analysis of the separate data alone. This methodology is termed integrated population modelling. A particular focus of this talk will be to discuss integrated population modelling for multisite data, which arises when animals live in and move between different locations. By making use of movement information provided by MRR data, it is possible to avoid flat likelihood surfaces, thus allowing the estimation of sitedependent parameters. The benefits of performing integrated population modelling on multisite data will be highlighted through both simulated and real data applications. 



Oct 18  Thu  Toby Reynolds (The National Centre for Statistical Ecology)  RSS Seminar  
14:30  Integrated data analysis in the presence of emigration and tag loss: A study of common guillemots on (and off) the Isle of May  
Hicks Room K14  
Abstract: In recent years, many UK seabird populations have experienced dramatic breeding failures and lower than average survival. The common guillemot (Uria aalge) is among those species to suffer. The causes of these events are likely due to a combination of overfishing and environmental change affecting their primary prey species, the lesser sandeel (Ammodytes marinus). We need to understand the dynamics of seabird populations, in order to determine the implications of future breeding failures and enable us to monitor or predict the effects of future changes in the marine environment. Integrated population modelling provides a useful and robust means to achieve this. An integrated analysis will be presented of four longterm datasets relating to a single guillemot colony on the Isle of May, southeast Scotland (a population of about 20,000 breeding pairs). These comprise abundance, MRR (two datasets) and productivity data. A particular complication with guillemot population dynamics arises due to unobservable emigration of immature birds. In traditional analyses using only MRR data, emigration is confounded with tag loss in the estimation of `fidelity' probabilities, and it is only possible to estimate their product. By combining all available data for the Isle of May guillemots, we are able to provide separate estimates for emigration and tag loss. This model provides a framework which may be used for prediction under various future scenarios. 



Oct 19  Fri  Urmila MitraKraev (Sheffield)  
13:05  
Lecture Theatre 9  


Oct 22  Mon  Paul Mitchener (Sheffield)  Noncommutative Geometry, Analysis and Groups  
17:00  Motivation and Introduction to the Index Theorem  
Hicks Seminar Room J11  
Abstract: We will look at de Rham cohomology, the Euler characteristic, differential operators, and the GaussBonnet formula in an attempt to motivate the AtiyahSinger index theorem before stating the theorem in its general form. The plan is for this to be a short talk; we will work out organisational details for the rest of the semester afterwards. 



Oct 26  Fri  Sergei Zharkov (Sheffield)  
13:05  
Lecture Theatre 9  


Oct 26  Fri  Almar Kaid (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Frobenius descent for vector bundles  
Hicks Seminar Room J11  


Oct 29  Mon  Bruce Bartlett  Higher Category Theory  
16:00  Degenerate Higher Categories II  
Hicks Seminar Room J11  
Abstract: This is part II of the talk from last week. I will recap the idea of the periodic table and what the stabilization hypothesis is about. Then we'll relate the ideas of suspension, looping, and stabilization in higher categories to the corresponding ideas in topology. Finally we'll look at the "second column" of the periodic table, explaining the kinds of algebraic structures which appear there  with plenty of examples (*)  and also explain how suspension and looping work on these structures. (*) One of the algebraic structures appearing in the second column of the periodic table is a "braided monoidal category". I will try to mention the idea due to Grothendieck and Drinfeld, once explained to me by Frazer, that the "group of deformations" of a certain natural braided monoidal category is somehow isomorphic to the absolute Galois group from number theory. 



Oct 29  Mon  John Greenlees (Sheffield)  Noncommutative Geometry, Analysis and Groups  
17:00  Characteristic Classes  
Hicks Seminar Room J11  


Oct 30  Tue  Shoham Shamir (Sheffield)  Topology Seminar  
14:00  Cellular approximations and the EilenbergMoore spectral sequence  
Hicks Seminar Room J11  
Abstract: Given chaincomplexes k and M over a ring R, a kcellular approximation to M is the "closest approximation" of M that can be glued together from copies of suspensions of k. I will discuss this concept (due to Dwyer, Greenlees and Iyengar) and how is can be used to study the EilenbergMoore cohomology spectral sequence for a fibration. 



Oct 31  Wed  Wilhelm Klingenberg (Durham)  Pure Maths Colloquium  
16:00  Fibrations by geodesics, spacelike surfaces, and the standard tight contact structure  
Hicks Seminar Room J11  
Abstract: A regular fibration by geodesics of a threedimensional space form is represented by a spacelike surface in fourdimensional moduli space of geodesics. In the euclidean case, the standard contact structure is perpendicular to such a fibration. Solemn undertaking: "I would make it accessible to any math grad student..." 



Oct 31  Wed  Professor Alan Zinober (Sheffield)  Applied Mathematics Colloquium  
16:00  'Optimal Control and Some Applications in Operations Research'  
Hicks Lecture Theatre 6  


Nov 2  Fri  Gemma Attrill (MSSL)  
13:05  
Lecture Theatre 9  


Nov 2  Fri  Barrie Cooper (Sheffield)  Algebra / Algebraic Geometry seminar  
14:10  Almost Koszul algebras and rational conformal field theory I  
Hicks Seminar Room J11  
Abstract: The preprojective algebra of a nonDynkin graph is Koszul and can be identified with the functorial image of a Koszul ``universal preprojective algebra object'' in the TemperleyLieb category. This line of thought also helps identify what happens to make the Dynkin preprojective algebras ``almost Koszul'' and elicits interesting connections to conformal field theory and quantum subgroups of sl(2). In the second talk I will discuss the sl(3) case and use these connections to construct new examples of almost Koszul algebras. The talk will be pretty basic, with the aim of rendering the abstract comprehensible to a graduate student. 



Nov 5  Mon  Richard Hepworth (Sheffield)  Noncommutative Geometry, Analysis and Groups  
17:00  Dirac Operators  
Hicks Seminar Room J11  


Nov 6  Tue  James Cranch (Sheffield)  Topology Seminar  
14:00  Spannish for beginners  
Hicks Seminar Room J11  
Abstract: I will say something about the notion of a span category, the appropriate analogue in the language of quasicategories, and what all this is supposed to have to do with homotopy theory. 



Nov 7  Wed  Bob Coecke (Oxford)  Pure Maths Colloquium  
16:00  Kindergarten Quantum Mechanics  
Hicks Seminar Room J11  


Nov 7  Wed  Dr C.J.Howls (Southampton)  Applied Mathematics Colloquium  
16:00  'Why is a Shock Not a Caustic?  
Hicks Lecture Theatre 6  


Nov 8  Thu  Markus Riedle (University of Manchester)  Statistics Seminar  
14:00  Introduction to stochastic delay differential equations  
Hicks Room K14  
Abstract: In the last years stochastic functional differential equations or stochastic differential equations with delay have gained increasing attention in several scientific areas such as economy, biology, physics and medicine. The reason can be found in the observation that in a huge variety of models the evolution of the process describing the dynamics in the model under consideration not only depends on the current state of the process but also on its former states. This effect is due to various reasons such as time to maturity, incubation time, time to build, time to transport, hysteresis, delayed feedback and past dependent volatility. In the beginning of the talk we present some of these applications of stochastic functional differential equations. We introduce the basic ideas of ordinary stochastic differential equations not depending on the past and explain how these equations can be generalised to functional equations covering the examples presented before. The fundamental theory of stochastic functional differential equations are introduced and in particular compared with the situation of ordinary stochastic differential equations. In the remaining part of the talk we distinguish several cases how the random noise and past dependence enter the equation and we focus here on asymptotic aspects of the solution. We present some phenomena only known from delay equations. We also introduce some results which explain the relation of functional and partial stochastic differential equations. 



Nov 9  Fri  Youra Taroyan (Sheffield)  
13:05  
Lecture Theatre 9  
