Forthcoming Seminars
|
Thu, 15/10/2009 14:30 |
Petter Bergh (NTNU Trondheim) |
Representation Theory Seminar  |
L3 |
| This is joint work with Steffen Oppermann. A cluster category is obtained from the bounded derived category of a hereditary algebra, by forming the orbit category with respect to the suspension and the Auslander-Reiten translate. We study the complexity between objects in this triangulated category, and show the following: the maximal complexity occurring is either one, two or infinite, depending on whether the original algebra is of finte, tame or wild representation type. Moreover, we show that the complexity of a module over a tame cluster tilted algebra is at most one. | |||
|
Thu, 15/10/2009 15:45 |
Gregory Sankaran (Bath) |
Algebraic and Symplectic Geometry Seminar |
SR2 |
| I shall describe joint work with Gritsenko and Hulek in which we study the moduli spaces of polarised holomorphic symplectic manifolds via their periods. There are strong similarities with moduli spaces of K3 surfaces, but also some important differences, notably that global Torelli fails. I shall explain (conjecturally) why and show how the techniques used to obtain general type results for K3 moduli can be modified to give similar, and quite strong, results in this case. Mainly I shall concentrate on the case of deformations of Hilbert schemes of K3 surfaces. | |||
|
Thu, 15/10/2009 16:30 |
Ricardo Carretero (San Diego State Univ) |
Differential Equations and Applications Seminar |
DH 1st floor SR |
| Traditional Faraday waves appear in a layer of liquid that is shaken vertically. These patterns can take the form of horizontal stripes, close-packed hexagons, or even squares or quasiperiodic patterns. Faraday waves are commonly observed as fine stripes on the surface of wine in a wineglass that is ringing like a bell when periodically forced. Motivated by recent experiments on Faraday waves in Bose-Einstein condensates we investigate both analytically and numerically the dynamics of cigar-shaped Bose-condensed gases subject to periodic modulation of the strength of the transverse confinement's trap. We offer a fully analytical explanation of the observed parametric resonance yielding the pattern periodicity versus the driving frequency. These results, corroborated by numerical simulations, match extremely well with the experimental observations. | |||
|
Thu, 15/10/2009 17:00 |
Jonathan Pila (Bristol) |
Logic Seminar |
L2 |
|
Fri, 16/10/2009 11:30 |
none |
Industrial and Interdisciplinary Workshops |
DH 3rd floor SR |
|
Fri, 16/10/2009 14:00 |
Dr Jan Kreft (University of Birmingham) |
Mathematical Biology and Ecology Seminar |
L3 |
|
Fri, 16/10/2009 14:15 |
Michael Kohlmann (Konstanz) |
Nomura Seminar |
DH 1st floor SR |
| We construct a market of bonds with jumps driven by a general marked point process as well as by an Rn-valued Wiener process, in which there exists at least one equivalent martingale measure Q0. In this market we consider the mean-variance hedging of a contingent claim H 2 L2(FT0) based on the self-financing portfolios on the given maturities T1, · · · , Tn with T0 < T1 < · · · < Tn T. We introduce the concept of variance-optimal martingale (VOM) and describe the VOM by a backward semimartingale equation (BSE). We derive an explicit solution of the optimal strategy and the optimal cost of the mean-variance hedging by the solutions of two BSEs. The setting of this problem is a bit unrealistic as we restrict the available bonds to those with a a pregiven finite number of maturities. So we extend the model to a bond market with jumps and a continuum of maturities and strategies which are Radon measure valued processes. To describe the market we consider the cylindrical and normalized martingales introduced by Mikulevicius et al.. In this market we the consider the exp-utility problem and derive some results on dynamic indifference valuation. The talk bases on recent common work with Dewen Xiong. | |||
|
Mon, 19/10/2009 12:00 |
Philip Candelas (Oxford) |
String Theory Seminar |
L3 |
| I will discuss a Calabi-Yau manifold which admits free actions by Abelian and non-Abelian groups of order 12. The quotient manifolds have Euler number -6 and Hodge numbers (h^{11}, h^{21}) = (1,4). Apart from the various presentations of the Yau Manifold, that have Hodge numbers (6,9), this is the only other complete intersection CY manifold to admit a free quotient with Euler number -6 and hence three generations of particles with the standard embedding. I will discuss the spectrum of light particles and the possibility of a transgression to a heterotic vacuum on a manifold with Hodge numbers (2,2). | |||
|
Mon, 19/10/2009 14:15 |
Alexander Lindner (Technische Universität Braunschweig) |
Stochastic Analysis Seminar |
Eagle House |
|
Mon, 19/10/2009 14:15 |
James Simons (Stony Brook) |
Geometry and Analysis Seminar |
L3 |
|
Mon, 19/10/2009 15:45 |
Dennis Sullivan (CUNY and Stony Brook) |
Topology Seminar |
L3 |
|
Mon, 19/10/2009 15:45 |
Marc Wouts (Université Paris13) |
Stochastic Analysis Seminar |
Eagle House |
|
Mon, 19/10/2009 16:00 |
Tim Trudgian (Mathematical Institute, Oxford) |
Junior Number Theory Seminar |
SR1 |
|
Mon, 19/10/2009 17:00 |
Grégoire Allaire (Ecole Polytechnique) |
Partial Differential Equations Seminar |
Gibson 1st Floor SR |
| We study the homogenization and singular perturbation of the wave equation in a periodic media for long times of the order of the inverse of the period. We consider inital data that are Bloch wave packets, i.e., that are the product of a fast oscillating Bloch wave and of a smooth envelope function. We prove that the solution is approximately equal to two waves propagating in opposite directions at a high group velocity with envelope functions which obey a Schrödinger type equation. Our analysis extends the usual WKB approximation by adding a dispersive, or diffractive, effect due to the non uniformity of the group velocity which yields the dispersion tensor of the homogenized Schrödinger equation. This is a joint work with M. Palombaro and J. Rauch. | |||
|
Tue, 20/10/2009 12:00 |
Alan Rendall (AEI Golm) |
Relativity Seminar |
L3 |
| Two classes of solutions of the Einstein equations with symmetry which are frequently studied are the Bianchi and Gowdy models. The aim of this talk is to explain certain relations between these two classes of spacetimes which can provide insights into the dynamics of both. In particular it is explained that the special case of the Gowdy models known as circular loop spacetimes are Bianchi models in disguise. Generalizations of Gowdy spacetimes which can be thought of as inhomogeneous perturbations of some of the Bianchi models are introduced. Results concerning their dynamics are presented. | |||
|
Tue, 20/10/2009 14:00 |
Balazs Szendroi (Oxford) |
Algebraic and Symplectic Geometry Seminar |
SR2 |
| I will talk about joint work with Dimca, respectively Behrend and Bryan, in which we refine the numerical DT-Behrend invariants of Hilbert schemes of threefolds by using vanishing cycle motives (a la Kontsevich-Soibelman) or mixed Hodge modules, leading to deformed MacMahon formulae. | |||
|
Tue, 20/10/2009 15:45 |
Balazs Szendroi (Oxford) |
Algebraic and Symplectic Geometry Seminar |
L3 |
| I will talk about joint work with Dimca, respectively Behrend and Bryan, in which we refine the numerical DT-Behrend invariants of Hilbert schemes of threefolds by using vanishing cycle motives (a la Kontsevich-Soibelman) or mixed Hodge modules, leading to deformed MacMahon formulae. | |||
|
Tue, 20/10/2009 16:00 |
Dawid Kielak |
Seminar |
DH 1st floor SR |
| We will discuss a connection between small cancellation conditions and isoperimetric inequalities. Additionally we shall look at a useful construction connecting small cancellation complexes and cube complexes. | |||
|
Tue, 20/10/2009 17:00 |
Kobi Kremnizer (Oxford) |
Algebra Seminar |
L2 |
|
Wed, 21/10/2009 10:10 |
Mokhles Mnejja |
Seminar |
OCCAM Common Room (RI2.28) |
