Forthcoming Seminars

Thu, 12/02/2009
17:00 		Marco Ferreira (East Anglia) Logic Seminar Add to calendar L3
The geometries of the Hrushovski constructions.
In 1993 in his paper "A new strongly minimal set" Hrushovski produced a family of counter examples to a conjecture by Zilber. Each one of these counter examples carry a pregeometry. We answer a question by Hrushovski about comparing these pregeometries and their localization to finite sets. We first analyse the pregeometries arising from different variations of the construction before the collapse. Then we compare the pregeometries of the family of new strongly minimal structures obtained after the collapse.
Fri, 13/02/2009
09:30 		Matt Telfer (Oxford) Industrial and Interdisciplinary Workshops Add to calendar DH 1st floor SR
Sand Dunes Workshop
Fri, 13/02/2009
14:15 		Monique Jeanblanc (Evry) Nomura Seminar Add to calendar DH 1st floor SR
Density models for credit risk
Seminar also with N. El Karoui and Y. Jiao Dynamic modelling of default time for one single credit has been largely studied in the literature. For the pricing and hedging purpose, it is important to describe the price dynamics of credit derivative products. To this end, one needs to characterize martingales in the various filtrations and calculate conditional expectations by taking into account of default information, often modelized by a filtration $ \bf{ D} $ generated by the jump process related to the default time $ \tau $. A general principle is to work with some reference filtration $ \bf F $ which is often generated by some given processes. The calculations are then achieved by a formal passage between the enlarged filtration and the reference one on the set $ \{\tau>t\} $ and the models are developed on the filtration $ \bf F $. In this paper, we are interested in what happens after a default occurs, i.e., on the set $ \{\tau\leq t\} $. The motivation is to study the impact of a default event on the market, which will be important in a multi-credits setting. To this end, we adopt a new approach which is based on the knowledge of conditional survival probabilities. Inspired by the enlargement of filtration theory, we assume that the conditional law of $ \tau $ admits a density. We also present how our computations can be used in a multi-default setting.
Fri, 13/02/2009
14:30 		Dr. Alison Rust (University of Bristol.) Mathematical Geoscience Seminar Add to calendar DH 3rd floor SR
Seismicity by flow in a deformable channel.
Fri, 13/02/2009
16:30 		Trevor Wood (University of Oxford) Junior Applied Mathematics Seminar Add to calendar DH 3rd floor SR
The Hunt For Red October: Mathematical Modelling of Submarine Tracking
Mon, 16/02/2009
12:00 		Andre Lukas (Oxford) String Theory Seminar Add to calendar L3
Yukawa Couplings from Monad Bundles
We present a straightforward, algebraic method for calculating the Yukawa couplings of a large class of non-standard embedding heterotic compactifications on Calabi-Yau threefolds. Our methodology covers, although is not restricted to, the positive monads over complete intersection Calabi-Yau manifolds. The algorithm involves the manipulation of polynomials and can be straightforwardly implemented on a computer. We present explicit examples and show how models with one Higgs multiplet and a rank-one mass matrix can be engineered.
Mon, 16/02/2009
14:15 		Professor Xunyu Zhou (Oxford) Stochastic Analysis Seminar Add to calendar Oxford-Man Institute
Non Expected Utility Maximisation
Mon, 16/02/2009
15:45 		Alain Valette (Universite de Neuchatel) Topology Seminar Add to calendar L3
Permanence properties of a-T-menability
Mon, 16/02/2009
15:45 		Dr Andrew Wade (Bristol) Stochastic Analysis Seminar Add to calendar Oxford-Man Institute
Stochastic billiards in unbounded planar domains
 Motivated by ideal gas models in the low density regime, we study a randomly reflecting particle travelling at constant speed in an unbounded domain in the plane with boundary satisfying a polynomial growth condition The growth rate of the domain, together with the reflection distribution, determine the asymptotic behaviour of the process. We give results on recurrence vs. transience, and on almost-sure-bounds for the particle including the rate of escape in the transient case. The proofs exploit a surprising relationship with Lamperti's problem of a process on the half-line with asymptotically zero drift. This is joint work with Mikhail Menshikov and Marina Vachkovskaia.
Mon, 16/02/2009
17:00 		Reiner Schätzle (Tübingen University) Partial Differential Equations Seminar Add to calendar Gibson 1st Floor SR
Minimizers of the Willmore functional under fixed conformal class
We prove the existence of a smooth minimizer of the Willmore energy in the class of conformal immersions of a given closed Riemann surface into $ R^n $, $ n = 3, 4 $, if there is one conformal immersion with Willmore energy smaller than a certain bound $ W_{n,p} $ depending on codimension and genus $ p $ of the Riemann surface. For tori in codimension $ 1 $, we know $ W_{3,1} = 8\pi $ . Joint work with Enrst Kuwert.
Tue, 17/02/2009
12:00 		Paul Sutcliffe (Durham) Quantum Field Theory Seminar Add to calendar L3
Solitonic Knots
Tue, 17/02/2009
14:15 		Jacob Rasmussen (Cambridge) Algebraic and Symplectic Geometry Seminar Add to calendar Higman Room
Flag varieties and the HOMFLY polynomial I
Khovanov homology is an invariant of knots in $ S^3 $. In its original form, it is a "homological version of the Jones polynomial"; Khovanov and Rozansky have generalized it to other knot polynomials, including the HOMFLY polynomial. The first talk will be an introduction to Khovanov homology and its generalizations.
Tue, 17/02/2009
14:30 		Dudley Stark (QMUL) Combinatorial Theory Seminar Add to calendar L3
The edge correlation of random forests
The conjecture was made by Pemantle that a forest chosen uniformly at random from all forests in any finite graph G has the edge-negative association property. We use enumerative methods to show that this conjecture is true for n large enough when G is a complete graph on n vertices and derive related results for random trees.
Tue, 17/02/2009
15:45 		Jacob Rasmussen (Cambridge) Algebraic and Symplectic Geometry Seminar Add to calendar L3
Flag varieties and the HOMFLY polynomial II
Khovanov homology is an invariant of knots in $ S^3 $. In its original form, it is a "homological version of the Jones polynomial"; Khovanov and Rozansky have generalized it to other knot polynomials, including the HOMFLY polynomial. In the second talk, I'll discuss how Khovanov homology and its generalizations lead to a relation between the HOMFLY polynomial and the topology of flag varieties.
Tue, 17/02/2009
17:00 		John Weir (King's College, London) Functional Analysis Seminar Add to calendar L3
A non-self-adjoint operator with real spectrum
Tue, 17/02/2009
17:00 		David Hernandez (Paris) Algebra Seminar Add to calendar L2
Monoidal categorification of cluster algebras
Wed, 18/02/2009
11:30 		David Craven (University of Oxford) Algebra Kinderseminar Add to calendar
Representation growth vs subgroup growth (Held in ChCh, Tom Gate, Room 2)
The subgroup growth of finitely generated groups was seen last term, in a lecture of Dan Segal. This time, we see representation growth, and how it is similar to, and different from, subgroup growth.

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

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