Forthcoming Seminars

Tue, 19/10/2010
17:00 		Paul Crewe (Oxford) Functional Analysis Seminar Add to calendar L3
Stochastic Delay Equations in UMD spaces
Wed, 20/10/2010
10:10 		Dr Soumyendu Raha (Indian Institute of Science) OCCAM Wednesday Morning Event Add to calendar OCCAM Common Room (RI2.28)
The alpha-method of numerical integration of ODEs and DAEs: regularization and multi-scale properties
We shall discuss a simple low order numerical integration scheme for ODEs and DAEs. The scheme has a parameter that allows for regularization of Jacobian of stiff problems and for numerically elucidating multi-scale response, if any, in some problems.
Wed, 20/10/2010
11:30 		Ben Davison (University of Oxford) Algebra Kinderseminar Add to calendar ChCh, Tom Gate, Room 2
Topology as Non-commutative Geometry
Wed, 20/10/2010
15:00 		Chris Blair (Cambridge) Junior Mathematical Physics Seminar Add to calendar Gibson 1st Floor SR
Constructing Singular Monopoles from Cheshire Bows

Singular monopoles are solutions to the Bogomolny equation with prescribed singularities of Dirac monopole type. Previously such monopoles could be constructed only by the Nahm transform, with some difficulty. We therefore formulate a new construction of all singular monopoles. This construction relies on two ideas: Kronheimer's correspondence between singular monopoles on R^3 and self-dual connections on the multi-Taub-NUT space, and Cherkis' recent construction of self-dual connections on curved spaces using bow diagrams. As an example of our method we use it to obtain the explicit solution for a charge one SU(2) singular monopole with an arbitrary number of singularities.
Thu, 21/10/2010
11:00 		Jonathan Pila (Oxford) Advanced Logic Class Add to calendar SR1
"O-minimality and diophantine problems".
Thu, 21/10/2010
11:00 		ABC - KLM Network Meeting Add to calendar ChCh, Tom Gate, Room 2
Test
$ \int_{0}^\infty $
Thu, 21/10/2010
12:45 		Mathematical Finance Internal Seminar Add to calendar DH 1st floor SR
1st year presentation
Thu, 21/10/2010
13:00 		Alan Thompson (University of Oxford) Junior Geometry and Topology Seminar Add to calendar SR1
Models for threefolds fibred by K3 surfaces of degree two
A K3 surface of degree two can be seen as a double cover of the complex projective plane, ramified over a nonsingular sextic curve. In this talk we explore two different methods for constructing explicit projective models of threefolds admitting a fibration by such surfaces, and discuss their relative merits.
Thu, 21/10/2010
14:00 		Prof. Axel Voigt (Dresden University of Technology) Computational Mathematics and Applications Add to calendar Gibson Grd floor SR
Diffuse interface models for two-phase flow
Starting from a Navier-Stokes-Cahn-Hilliard equation for a two-phase flow problem we discuss efficient numerical approaches based on adaptive finite element methods. Various extensions of the model are discussed: a) we consider the model on implicitly described geometries, which is used to simulate the sliding of droplets over nano-patterned surfaces, b) we consider the effect of soluble surfactants and show its influence on tip splitting of droplets under shear flow, and c) we consider bijels as a new class of soft matter materials, in which colloidal particles are jammed on the fluid-fluid interface and effect the motion of the interface due to an elastic force. The work is based on joint work with Sebastian Aland (TU Dresden), John Lowengrub (UC Irvine) and Knut Erik Teigen (U Trondheim).
Thu, 21/10/2010
14:30 		David Craven (Oxford) Representation Theory Seminar Add to calendar L3
Perverse equivalences and the Broue conjecture
Thu, 21/10/2010
16:00 		Dr A Gorodnik (Bristol) Number Theory Seminar Add to calendar L3
Almost prime points on homogeneous varieties
Given a polynomial function f defined on a variety X, we consider two questions, which are non-commutative analogues of the Prime Number Theorem and the Linnik Theorem: - how often the values of f(x) at integral points in X are almost prime? - can one effectively solve the congruence equation f(x)=b (mod q) with f(x) being almost prime? We discuss a solution to these questions when X is a homogeneous variety (e.g, a quadratic surface).
Thu, 21/10/2010
16:00 		Darryl D Holm ((Imperial College, London)) Differential Equations and Applications Seminar Add to calendar DH 1st floor SR
The shape of water, metamorphosis and infinite-dimensional geometric mechanics
Whenever we say the words "fluid flows" or "shape changes" we enter the realm of infinite-dimensional geometric mechanics. Water, for example, flows. In fact, Euler's equations tell us that water flows a particular way. Namely, it flows to get out of its own way as adroitly as possible. The shape of water changes by smooth invertible maps called diffeos (short for diffeomorphisms). The flow responsible for this optimal change of shape follows the path of shortest length, the geodesic, defined by the metric of kinetic energy. Not just the flow of water, but the optimal morphing of any shape into another follows one of these optimal paths. The lecture will be about the commonalities between fluid dynamics and shape changes and will be discussed in the language most suited to fundamental understanding – the language of geometric mechanics. A common theme will be the use of momentum maps and geometric control for steering along the optimal paths using emergent singular solutions of the initial value problem for a nonlinear partial differential equation called EPDiff, that governs metamorphosis along the geodesic flow of the diffeos. The main application will be in the registration and comparison of Magnetic Resonance Images for clinical diagnosis and medical procedures.
Thu, 21/10/2010
17:00 		Wilfrid Hodges Logic Seminar Add to calendar L3
'Proof of Gaifman's conjecture for relatively categorical abelian groups'
In 1974 Haim Gaifman conjectured that if a first-order theory T is relatively categorical over T(P) (the theory of the elements satisfying P), then every model of T(P) expands to one of T. The conjecture has long been known to be true in some special cases, but nothing general is known. I prove it in the case of abelian groups with distinguished subgroups. This is some way outside the previously known cases, but the proof depends so heavily on the Kaplansky-Mackey proof of Ulm's theorem that the jury is out on its generality.
Fri, 22/10/2010
14:15 		Ronnie Sircar (Princeton University) Nomura Seminar Add to calendar DH 1st floor SR
Optimal Static-Dynamic Hedging under Convex Risk Measures
The theory and computation of convex measures of financial risk has been a very active area of Financial Mathematics, with a rich history in a short number of years. The axioms specify sensible properties that measures of risk should possess (and which the industry's favourite, value-at-risk, does not). The most common example is related to the expectation of an exponential utility function. A basic application is hedging, that is taking off-setting positions, to optimally reduce the risk measure of a portfolio. In standard continuous-time models with dynamic hedging, this leads to nonlinear PDE problems of HJB type. We discuss so-called static-dynamic hedging of exotic options under convex risk measures, and specifically the existence and uniqueness of an optimal position. We illustrate the computational challenge when we move away from the risk measure associated with exponential utility. Joint work with Aytac Ilhan (Goldman Sachs) and Mattias Jonsson (University of Michigan).
Fri, 22/10/2010
14:30 		John Norbury and Anthony Lock (OCIAM) Mathematical Geoscience Seminar Add to calendar DH 3rd floor SR
'Exact solutions of a column model as an inner loop in global climate modelling.'
Fri, 22/10/2010
16:30 		Nicola Fusco Colloquia Add to calendar L2
The sharp quantitative isoperimetric inequality and related inequalities in quantitative form.
The isoperimetric inequality is a fundamental tool in many geometric and analytical issues, beside being the starting point for a great variety of other important inequalities. We shall present some recent results dealing with the quantitative version of this inequality, an old question raised by Bonnesen at the beginning of last century. Applications of the sharp quantitative isoperimetric inequality to other classic inequalities and to eigenvalue problems will be also discussed.
Mon, 25/10/2010
03:45 		Udo Hertrich-Jeromin (Bath) Topology Seminar Add to calendar L3
Discrete differential geometry: constant mean curvature surfaces
The is the second part of the Analysis and Geometry Seminar today.
Mon, 25/10/2010
12:00 		Ron Reid-Edwards (Oxford) String Theory Seminar Add to calendar L3
On the gravity duals of N=2 superconformal field theories
In 2009 Gaiotto and Maldacena demonstrated that the challenge of finding gravitational descriptions of N=2 superconformal field theories could, under certain circumstances, be reduced to a simple two-dimensional electrostatics problem. In this talk I will review their work and discuss recent progress in finding and interpreting such solutions in string and M-theory.

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

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