Thu, 01 Mar 2007

14:00 - 15:00
Comlab

Linear and nonlinear semidefinite programs in structural optimization

Prof Michal Kocvara
(University of Birmingham)
Abstract

Several formulations of structural optimization problems based on linear and nonlinear semidefinite programming will be presented. SDP allows us to formulate and solve problems with difficult constraints that could hardly be solved before. We will show that sometimes it is advantageous to prefer a nonlinear formulation to a linear one. All the presented formulations result in large-scale sparse (nonlinear) SDPs. In the second part of the talk we will show how these problems can be solved by our augmented Lagrangian code PENNON. Numerical examples will illustrate the talk.

Joint work with Michael Stingl.

Wed, 28 Feb 2007
16:00
L3

On possible non-homeomorphic substructures of the real line.

Philip Welch
(Bristol)
Abstract

 

We consider as a starting point a problem raised by Kunen and Tall as to whether

the real continuum can have non-homeomorphic versions in different submodels of

the universe of all sets. Its resolution depends on modest large cardinals.

In general Junqueira and Tall have made a study of such "substructure spaces"

where the topology of a subspace can be different from the usual relative

topology.

Tue, 27 Feb 2007
17:00
L1

Spectra of Groups

Professor Andrzej Zuk
(Paris & Newton Inst.)
Tue, 27 Feb 2007
12:00
L3

J vs m

Piotr Chrusciel
(Oxford)
Abstract
  We will shortly review the known bounds on the angular momentum J in terms of mass m assuming a negative cosmological constant, and describe in more detail Brill's proof of the axisymmetric positive energy theorem, and Dain's upper bound on angular momentum J for vacuum initial data sets with an axial Killing vector and with two asymptotically flat regions.
Mon, 26 Feb 2007
15:45
DH 3rd floor SR

On linear and nonlinear interacting particle systems

Mr Lihu Xu
(Imperial College, London)
Abstract
  We start from the stochastic Ising model(or Glauber Dynamics) and have a short review of some important topics in Particle Systems such as ergodicity, convergence rates and so on. Then an abstract nonlinear model will be introduced by an evolution differential equation. We will build the existence and uniqueness theorem, and give some nice properties such as convergence exponentially and monotonicity for the abstract systems. To apply our abstract theory, we will study a family of nonlinear interacting particle systems generalized from Glauber Type Dynamics(we call them nonlinear Glauber Type Dynamics) and prove that such generalization can be done in infinitely many ways. For nonlinear Glauber Type Dynamics, we have two interesting inequalities related to Gibbs measures. Finally, we will concentrate on one specific nonlinear dynamics, and provide the relation between nonlinear system and the linear one, and that between Gibbs measures and tangent functionals to a nonlinear transfer operator.
Mon, 26 Feb 2007
14:15
DH 3rd floor SR

Markov loops, determinants and Gaussian fields

Prof Yves Le Jan
(University of Paris XI)
Abstract

 

We will see how Dynkin's isomorphism emerges from the "loop soup" introduced by

Lawler and Werner.