Forthcoming Seminars
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Mon, 19/01/2004 14:15 |
David Calderbank (Edinburgh) |
Geometry and Analysis Seminar  |
L3 |
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Mon, 19/01/2004 14:15 |
Terry Lyons (Oxford) |
Stochastic Analysis Seminar |
DH 3rd floor SR |
| After a brief introduction to the basics of Rough Paths I'll explain recent work by Peter Friz, Dan Stroock and myself proving that a Brownian path conditioned to be uniformly close to a given smooth path converges in distribution to that path in the Rough Path metric. The Stroock Varadhan support theorem is an immediate consequence. The novel part of the argument is to obtain the estimate in a way that is independent of the particular norm used in the Euclidean space when one defines the uniform norm on path space. | |||
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Mon, 19/01/2004 15:45 |
Stella Brassesco (Warwick) |
Stochastic Analysis Seminar |
DH 3rd floor SR |
| We consider the Cahn Hilliard Equation in the line, perturbed by the space derivative of a space--time white noise. We study the solution of the equation when the initial condition is the interface, in the limit as the intensity of the noise goes to zero and the time goes to infinity conveniently, and show that in a scale that is still infinitesimal, the solution remains close to the interface, and the fluctuations are described by a non Markovian self similar Gaussian process whose covariance is computed. | |||
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Mon, 19/01/2004 17:00 |
John Bryden (Southern Illinois & Liverpool) |
Topology Seminar |
L3 |
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Tue, 20/01/2004 12:00 |
Dr M Hamanaka (Tokyo) |
Relativity Seminar |
L3 |
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Tue, 20/01/2004 15:00 |
Dillon Mayhew |
Combinatorial Theory Seminar |
L3 |
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Tue, 20/01/2004 17:00 |
Dr C Voll (Oxford) |
Algebra Seminar |
L1 |
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Wed, 21/01/2004 12:00 |
Peter West (King's College London) |
String Theory Seminar |
NAPL |
| After a review of the symmetries of supergravity theories and Kac-Moody algebras, we explain show that M theory is likely to possess a very large Kac-Moody symmetry of rank eleven, denoted by E_{11}. We also provide evidence that even pure gravity and the closed bosonic string possess analogous Kac-Moody symmetries. Finally, we explain how the central charges of the maximal supergravity theories arise naturally in E_{11}. | |||
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Thu, 22/01/2004 11:00 |
G Jones (Oxford) |
Advanced Logic Class |
L3 |
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Thu, 22/01/2004 14:00 |
Prof Simon Chandler-Wilde (University of Reading) |
Computational Mathematics and Applications |
Rutherford Appleton Laboratory, nr Didcot |
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We consider the problem of recovering the position of a scattering surface
from measurements of the scattered field on a finite line above the surface.
A point source algorithm is proposed, based on earlier work by Potthast,
which reconstructs, in the first instance, the scattered field in the whole
region above the scattering surface. This information is used in a second
stage to locate the scatterer. We summarise the theoretical results that can
be obtained (error bounds on the reconstructed field as a function of the
noise level in the original measurements). For the case of a point source of
the incident field we present numerical experiments for both a steady source
(time harmonic excitation) and a pulse source typical of an antenna in
ground penetrating radar applications.
This is joint work with Claire Lines (Brunel University). |
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Thu, 22/01/2004 16:30 |
Gihan Marasingha (Oxford) |
Number Theory Seminar |
L3 |
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Thu, 22/01/2004 16:30 |
John Allen (Oxford) |
Differential Equations and Applications Seminar |
DH Common Room |
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Fri, 23/01/2004 14:15 |
Giulia Iori (King's College, London) |
Mathematical Finance Seminar |
DH 3rd floor SR |
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Fri, 23/01/2004 15:15 |
T Pheidas (Crete) |
Logic Seminar |
SR1 |
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Mon, 26/01/2004 12:00 |
Mark Gross (Warwick) |
String Theory Seminar |
L3 |
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Mon, 26/01/2004 14:15 |
Mark Gross (Warwick) |
Geometry and Analysis Seminar |
L3 |
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Mon, 26/01/2004 14:15 |
Anita Wilson |
Stochastic Analysis Seminar |
DH 3rd floor SR |
| We consider a system of interacting Fisher-Wright diffusions which arise in population genetics as the diffusion limit of a spatial particle model in which frequencies of genetic types are changing due to migration and reproduction. For both models the historical processes are constructed, which record the family structure and the paths of descent through space. For any fixed time, particle representations for the historical process of a collection of Moran models with increasing particle intensity and of the limiting interacting Fisher-Wright diffusions are provided on one and the same probability space by means of Donnelly and Kurtz's look-down construction. It will be discussed how this can be used to obtain new results on the long term behaviour. In particular, we give representations for the equilibrium historical processes. Based on the latter the behaviour of large finite systems in comparison with the infinite system is described on the level of the historical processes. The talk is based on joint work with Andreas Greven and Vlada Limic. | |||
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Mon, 26/01/2004 15:45 |
Mathew Penrose |
Stochastic Analysis Seminar |
DH 3rd floor SR |
| Consider a graph with n vertices placed randomly in the unit square, each connected by an edge to its nearest neighbour in a south-westerly direction. For many graphs of this type, the centred total length is asymptotically normal for n large, but in the present case the limit distribution is not normal, being defined in terms of fixed-point distributions of a type seen more commonly in the analysis of algorithms. We discuss related results. This is joint work with Andrew Wade. | |||
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Mon, 26/01/2004 17:00 |
Jim Howie (Heriot Watt) |
Topology Seminar |
L3 |
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Mon, 26/01/2004 17:00 |
Jonathan Bevan (Oxford) |
Applied Analysis and Mechanics Seminar |
L1 |
| Using a technique explored in unpublished work of Ball and Mizel I shall show that already in 2 and 3 dimensions there are vectorfields which are singular minimizers of integral functionals whose integrand is strictly polyconvex and depends on the gradient of the map only. The analysis behind these results gives rise to an interesting question about the relationship between the regularity of a polyconvex function and that of its possible convex representatives. I shall indicate why this question is interesting in the context of the regularity results above and I shall answer it in certain cases. | |||
