Forthcoming Seminars

Thu, 06/05/2010
14:30 		Dusko Bogdanic (Oxford) Representation Theory Seminar Add to calendar L3
Graded Blocks of Group Algebras
We introduce the idea of transfer of gradings via derived equivalences and we apply it to construct positive gradings on a basic Brauer tree algebra corresponding to an arbitrary Brauer tree T. We do this by transferring gradings via derived equivalence from a basic Brauer tree algebra, whose tree is a star. To transfer gradings via derived equivalence we use tilting complexes constructed by taking Green's walk around T. We also prove that there is a unique grading on an arbitrary Brauer tree algebra, up to graded Morita equivalence and rescaling.
Thu, 06/05/2010
16:30 		Arezki Boudaoud (Department of Biology Ecole Normale Supérieure de Lyon) Differential Equations and Applications Seminar Add to calendar DH 1st floor SR
Modelling plant growth
How does form emerge from cellular processes? Using cell-based mechanical models of growth, we investigated the geometry of leaf vasculature and the cellular arrangements at the shoot apex. These models incorporate turgor pressure, wall mechanical properties and cell division. In connection with experimental data, they allowed us to, on the one hand, account for characteristic geometrical property of vein junctions, and, on the other hand, speculate that growth is locally regulated.
Thu, 06/05/2010
17:00 		Luc Belair (Montreal/Paris) Logic Seminar Add to calendar L3
Definability in valued Ore modules
We consider valued fields with a distinguished isometry or contractive derivation, as valued modules over the Ore ring of difference operators. This amounts to study linear difference/differential equations with respect to the distinguished isometry/derivation. Under certain assumptions on the residue field, but in all characteristics, we obtain quantifier elimination in natural languages, and the absence of the independence property. We will consider other operators of interest.
Fri, 07/05/2010
10:00 		Various (Engineering) Industrial and Interdisciplinary Workshops Add to calendar
Engineering Surgery session
Note this event is in the Thom Conference Room, Thom Building, Engineering Department 10am Prof David Edwards 10:30am Dr Alexander Korsunsky 11am Dr Zhong You
Fri, 07/05/2010
14:15 		Dana Rose-Anne (Joint With OMI) (Dauphine) Nomura Seminar Add to calendar DH 1st floor SR
Efficiency for the concave Order and Multivariate
comonotonicity joint work with Carlier and Galichon Abstact This paper studies efficient risk-sharing rules for the concave dominance order. For a univariate risk, it follows from a comonotone dominance principle, due to Landsberger and Meilijson that efficiency is characterized by a comonotonicity condition. The goal of the paper is to generalize the comonotone dominance principle as well as the equivalence between efficiency and comonotonicity to the multi-dimensional case. The multivariate case is more involved (in particular because there is no immediate extension of the notion of comonotonicity) and it is addressed by using techniques from convex duality and optimal transportation.
Fri, 07/05/2010
14:30 		Dr Peter Bollada, Cardiff (Cardiff) Mathematical Geoscience Seminar Add to calendar DH 3rd floor SR
Visco-elastic modelling for the generation of plate-like behaviour in the mantle.
Mon, 10/05/2010
12:00 		Masahito Yamazaki (Tokyo) String Theory Seminar Add to calendar L3
Crystal Melting and Wall Crossing for Donaldson-Thomas Invariants
I will describe the wall crossing phenomena for (generalized) Donaldson-Thomas invariants (also known as BPS invariants) from a physicist's perspective; the topics include crystal melting and its thermodynamic limit, M-theory derivation of wall crossing, and open wall crossing.
Mon, 10/05/2010
14:15 		Tobias Ekholm (Uppsala) Geometry and Analysis Seminar Add to calendar L3
Surgery and contact- and symplectic- homology
Mon, 10/05/2010
15:45 		Anne Thomas (Oxford) Topology Seminar Add to calendar L3
Surface quotients of hyperbolic buildings
Bourdon's building is a negatively curved 2-complex built out of hyperbolic right-angled polygons. Its automorphism group is large (uncountable) and remarkably rich. We study, and mostly answer, the question of when there is a discrete subgroup of the automorphism group such that the quotient is a closed surface of genus g. This involves some fun elementary combinatorics, but quickly leads to open questions in group theory and number theory. This is joint work with David Futer.
Mon, 10/05/2010
15:45 		Michal Ledoux (University of Toulouse) Stochastic Analysis Seminar Add to calendar Eagle House
The Geometry of Convolution Inequalities
Mon, 10/05/2010
16:00 		Damiano Testa (University of Oxford) Junior Number Theory Seminar Add to calendar SR1
An introduction to modular curves
Mon, 10/05/2010
17:00 		Robert Pego (Carnegie Mellon University) Partial Differential Equations Seminar Add to calendar Gibson 1st Floor SR
Spectral stability for solitary water waves 
I will recount progress regarding the robustness of solitary waves in
nonintegrable Hamiltonian systems such as FPU lattices, and discuss 
a proof (with Shu-Ming Sun) of spectral stability of small
solitary waves for the 2D Euler equations for water of finite depth
without surface tension.
Tue, 11/05/2010
12:00 		Katherine Mack (Cambridge) Quantum Field Theory Seminar Add to calendar L3
Axions, Inflation and the Anthropic Principle
The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation, high symmetry-breaking scales (such as those favored in string-theoretic axion models) are ruled out by cosmological constraints unless both the axion misalignment angle and the inflationary Hubble scale are extremely fine-tuned. I will discuss how attempting to accommodate a high-scale axion in inflationary cosmology leads to a fine-tuning problem that is worse than the strong-CP problem the axion was originally invented to solve, and how this problem is exacerbated when additional axion-like fields from string theory are taken into account. This problem remains unresolved by anthropic selection arguments commonly applied to the high-scale axion scenario.
Tue, 11/05/2010
14:15 		Richard Wood (University of Cambridge) Geophysical and Nonlinear Fluid Dynamics Seminar Add to calendar Dobson Room, AOPP
Mixing, jet sharpening and angular momentum in shallow atmospheres
Tue, 11/05/2010
15:45 		Tobias Ekholm (Uppsala) Algebraic and Symplectic Geometry Seminar Add to calendar L3
Symplectic homology of 4-dimensional Weinstein manifolds and Legendrian homology of links
We show how to compute the symplectic homology of a 4-dimensional Weinstein manifold from a diagram of the Legendrian link which is the attaching locus of its 2-handles. The computation uses a combination of a generalization of Chekanov's description of the Legendrian homology of links in standard contact 3-space, where the ambient contact manifold is replaced by a connected sum of $ S^1\times S^2 $'s, and recent results on the behaviour of holomorphic curve invariants under Legendrian surgery.
Tue, 11/05/2010
16:00 		Andrew Sale (Oxford) Junior Geometric Group Theory Seminar Add to calendar SR1
The Asymptotic Cone of a Symmetric Space is a Euclidean Building
I will introduce Symmetric spaces via a result of Kleiner & Leeb, comparing the axioms in their definition of a Euclidean building with properties of symmetric spaces of noncompact type.
Tue, 11/05/2010
17:00 		Sam Elliott (Leeds) Functional Analysis Seminar Add to calendar L3
Composition Operators on the Half-plane
Tue, 11/05/2010
17:00 		Peter Cameron (Queen Mary University) Algebra Seminar Add to calendar L2
Power graphs of groups and other magmas
Wed, 12/05/2010
10:10 		Dr Roman Potsepaev (Dr Roman Potsepaev) OCCAM Special Seminar Add to calendar OCCAM Common Room (RI2.28)
An Introduction to multi-level simulation methods for problems with distorted grids or tensor coefficients

For any corrections/updates to these listings, please contact seminars [-at-] maths [dot] ox [dot] ac [dot] uk.

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