Forthcoming Seminars
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Thu, 06/11/2008 16:00 |
David Solomon (Kings College London) |
Number Theory Seminar  |
L3 |
| "Stickelberger's famous theorem (from 1890) gives an explicit ideal which annihilates the imaginary part of the class group of an abelian field as a module for the group-ring of the Galois group. In the 1980s Tate and Brumer proposed a generalisation of Stickelberger's Theorem (and his ideal) to other abelian extensions of number fields, the so-called `Brumer-Stark conjecture'. I shall discuss some of the many unresolved issues connected with the annihilation of class groups of number fields. For instance, should the (generalised) Stickelberger ideal be the full annihilator, the Fitting ideal or what? And what can we say in the plus part (where Stickelberger's Theorem is trivial)?" | |||
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Thu, 06/11/2008 16:30 |
Nigel Mottram (Strathclyde) |
Differential Equations and Applications Seminar |
DH 1st floor SR |
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Fri, 07/11/2008 10:00 |
Betty Scheu (University of Munich) |
Industrial and Interdisciplinary Workshops |
DH 1st floor SR |
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Fri, 07/11/2008 14:15 |
Dilip Madan (Maryland) |
Mathematical Finance Seminar |
DH 1st floor SR |
| Stress levels embedded in S&P 500 options are constructed and re-ported. The stress function used is MINMAXV AR: Seven joint laws for the top 50 stocks in the index are considered. The first time changes a Gaussian one factor copula. The remaining six employ correlated Brownian motion independently time changed in each coordinate. Four models use daily returns, either run as Lévy processes or scaled, to the option maturity. The last two employ risk neutral marginals from the V GSSD and CGMY SSD Sato processes. The smallest stress function uses CGMY SSD risk neutral marginals and Lévy correlation. Running the Lévy process yields a lower stress surface than scaling to the option maturity. Static hedging of basket options to a particular level of accept- ability is shown to substantially lower the price at which the basket option may be o¤ered. | |||
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Fri, 07/11/2008 14:30 |
Professor Paul Tackley (ETH Zurich) |
Mathematical Geoscience Seminar |
DH 3rd floor SR |
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Fri, 07/11/2008 16:30 |
Professor Ofer Zeitouni (University of Minnesota and Weizmann Institute of Israel) |
Colloquia |
L1 |
| A random environment (in Z^d) is a collection of (random) transition probabilities, indexed by sites. Perform now a random walk using these transitions. This model is easy to describe, yet presents significant challenges to analysis. In particular, even elementary questions concerning long term behavior, such as the existence of a law of large numbers, are open. I will review in this talk the model, its history, and recent advance, focusing on examples of unexpected behavior. | |||
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Mon, 10/11/2008 12:00 |
Andrew Dancer (Oxford) |
String Theory Seminar |
L3 |
| Abstract: We produce new examples of steady and expanding Ricci solitons which are not of Kahler type. | |||
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Mon, 10/11/2008 14:15 |
Dr. Antal Jarai (Bath) |
Stochastic Analysis Seminar |
Oxford-Man Institute |
| The uniform spanning forest (USF) in a graph is a random spanning forest obtained as the limit of uniformly chosen spanning trees on finite subgraphs. The USF is known to have stochastic dimension 4 on graphs that are "at least 4 dimensional" in a certain sense. In this talk I will look at more detailed estimates on the geometry of a fixed component of the USF in the special case of the d-dimensional integer lattice, d > 4. This is motivated in part by the study of random walk restricted to a fixed component of the USF. | |||
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Mon, 10/11/2008 14:15 |
Thomas Schick (Goettingen) |
Geometry and Analysis Seminar K-Theory Day |
L3 |
| Let M be a closed spin manifold. Gromov and Lawson have shown that the presence of certain "enlargeable" submanifolds of codimension 2 is an obstruction to the existence of a Riemannian metric with positive scalar curvature on M. In joint work with Hanke, we refine the geoemtric condition of "enlargeability": it suffices that a K-theoretic index obstruction of the submanifold doesn't vanish. A "folk conjecture" asserts that all index type obstructions to positive scalar curvature should be read off from the corresponding index for the ambient manifold M (this this is equivalent to a small part of the strong Novikov conjecture). We address this question for the obstruction above and discuss partial results. | |||
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Mon, 10/11/2008 15:45 |
Siegfried Echterhoff (Goettingen) |
K-Theory Day Topology Seminar |
L3 |
| We study non-commutative analogues of Serre-ï¬~Abrations in topology. We shall present several examples of such ï¬~Abrations and give applications for the computation of the K-theory of certain C*-algebras. (Joint work with Ryszard Nest and Herve Oyono-Oyono.) | |||
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Mon, 10/11/2008 15:45 |
Mr. Balazs Rath (Budapest University of Technology and Economics) |
Stochastic Analysis Seminar |
Oxford-Man Institute |
| We modify the usual Erdos-Renyi random graph evolution by letting connected clusters 'burn down' (i.e. fall apart to disconnected single sites) due to a Poisson flow of lightnings. In a range of the intensity of rate of lightnings, the system sticks to a permanent critical state (i.e. exhibits so-called self-organised critical behaviour). The talk will be based on joint work with Balint Toth. | |||
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Mon, 10/11/2008 16:00 |
Jaha Zahid (Mathematical Insitute, Oxford) |
Junior Number Theory Seminar |
SR1 |
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Mon, 10/11/2008 17:00 |
Richard Szabo (Heriot Watt University) |
Topology Seminar |
L3 |
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Mon, 10/11/2008 17:00 |
Demetrios Christodoulou (ETH Zurich) |
Partial Differential Equations Seminar |
Gibson 1st Floor SR |
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Tue, 11/11/2008 12:00 |
Graeme Segal |
Quantum Field Theory Seminar |
L3 |
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Tue, 11/11/2008 14:30 |
Colin McDiarmid (Oxford) |
Combinatorial Theory Seminar |
L3 |
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Tue, 11/11/2008 15:45 |
Algebraic and Symplectic Geometry Seminar |
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Tue, 11/11/2008 17:00 |
Lars Olsen (St Andrews) |
Functional Analysis Seminar |
L3 |
| The talk will give two entirely different answers to the question asked in the title of the talk. A topological answer will be based on the classical notion of Baire category. A measure theoretical answer will be based on the much newer notion of prevalence/shyness. | |||
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Wed, 12/11/2008 10:45 |
Amit Acharya (Carnegie Mellon University) |
OxPDE Lunchtime Seminar |
Gibson 1st Floor SR |
| The question of local existence of a deformation of a simply connected body whose Left Cauchy Green Tensor matches a prescribed, symmetric, positive definite tensor field is considered. A sufficient condition is deduced after formulation as a problem in Riemannian Geometry. The compatibility condition ends up being surprisingly different from that of compatibility of a Right Cauchy Green Tensor field, a fact that becomes evident after the geometric formulation. The question involves determining conditions for the local existence of solutions to an overdetermined system of Pfaffian PDEs with algebraic constraints that is typically not completely integrable. | |||
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Wed, 12/11/2008 11:30 |
David Craven (University of Oxford) |
Algebra Kinderseminar |
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