Tue, 24 Nov 2015

14:00 - 14:30
L5

Numerical calculation of permanents

Peter McCullagh
(University of Chicago)
Abstract
The $\alpha$-permanent of a square matrix is a determinant-style sum, with $\alpha=-1$ corresponding to the determinant, $\alpha=1$ to the ordinary permanent, and $\alpha=0$ to the Hamiltonian sum over cyclic permutations.  Exact computation of permanents is notoriously difficult; numerical computation using the best algorithm for $\alpha=1$ is feasible for matrices of order about 25--30; numerical computation for general $\alpha$ is feasible only for $n < 12$.  I will describe briefly how the $\alpha$-permanent arises in statistical work as the probability density function of the Boson point process, and I will discuss the level of numerical accuracy needed for statistical applications.  My hope is that, for sufficiently large matrices, it may be possible to develop a non-stochastic polynomial-time approximation of adequate accuracy.
Mon, 23 Nov 2015

17:00 - 18:00
St Catherine's

How Long is a Piece of Spacetime

Professor Philip Bond
(Quantitative Software Consulting)
Abstract

 On November 25th 1915 Albert Einstein submitted his famous paper on the General Theory of Relativity. David Hilbert also derived the General Theory in November 1915 using quite different methods. In the same year Emmy Noether derived her remarkable ‘Noether’s Theorem’ which lies at the heart of much modern Physics. 1915 was a very good vintage indeed. We will take a brief walking tour of General Relativity using some of the ideas of Noether, Hilbert and Einstein to examine gravitational redshift, gravitational lensing, the impact of General Relativity on GPS systems and high precision atomic clocks, and Black holes all of which can be summarised by asking ‘how long is a piece of spacetime?’ 

Mon, 16 Nov 2015

16:00 - 17:00
L2

The Stokes-Fourier equations as scaling limit of the hard sphere dynamics

Laure Saint-Raymond
(Ecole Normale Superieure)
Abstract
In his sixth problem, Hilbert asked for an axiomatization of gas dynamics, and he suggested to use the Boltzmann equation as an intermediate description between the (microscopic) atomic dynamics and (macroscopic) fluid models. The main difficulty to achieve this program is to prove the asymptotic decorrelation between the local microscopic interactions, referred to as propagation of chaos, on a time scale much larger than the mean free time. This is indeed the key property to observe some relaxation towards local thermodynamic equilibrium.

 

This control of the collision process can be obtained in fluctuation regimes. In a recent work with I. Gallagher and T. Bodineau, we have established a long time convergence result to the linearized Boltzmann equation, and eventually derived the acoustic and incompressible Stokes equations in dimension 2. The proof relies crucially on symmetry arguments, combined with a suitable pruning procedure to discard super exponential collision trees.
Wed, 02 Mar 2016
15:00

Cryptographic Algorithms Used in Trusted Platform Modules

Liqun Chen
(Hewlett Packard Labs)
Abstract

Trusted Platform Modules (TPMs) are currently used in large numbers of computers. In this talk, I will discuss the cryptographic algorithms supported by the current version of the Trusted Platform Modules (Version 1.2) and also those due to be included in the new version  (Version 2.0).  After briefly introducing the history of TPMs, and the difference between these two generations TPMs, I will focus on the challenges faced in developing Direct Anonymous Attestation (DAA) an algorithmic scheme designed to preserve privacy and included in TPMs.

Mon, 30 Nov 2015

16:00 - 17:00
C2

TBA

Simon Rydin Myerson
(Oxford)
Wed, 24 Feb 2016
15:00
L4

Pairing-based Succinct Non-interactive Arguments

Jens Groth
(University College, London)
Abstract
Zero-knowledge proofs enable a prover to convince a verifier that a statement is true without revealing anything but the truth of the statement. In recent years there has been a lot of effort in making the proofs succinct, i.e., the proof may be much smaller than the statement itself and be very easy for the verifier to check. The talk will give a general introduction to zero-knowledge proofs and a presentation of a new pairing-based succinct non-interactive argument system.
Complete generalized Gibbs ensembles in an interacting theory
 Ilievski, E De Nardis, J Wouters, B Caux, J Essler, F Prosen, T Physical Review Letters volume 115 issue 15 (07 Oct 2015)
Mon, 09 Nov 2015

12:00 - 13:00
L3

Yang-Mills origin of gravitational symmetries

Mike Duff
(Imperial College)
Abstract

By regarding gravity as the convolution of left and right Yang-Mills theories together with a spectator scalar field in the bi-adjoint representation, we derive in linearised approximation the gravitational symmetries of general covariance, p-form gauge invariance, local Lorentz invariance and local supersymmetry from the flat space Yang-Mills symmetries of local gauge invariance and global super-Poincare. As a concrete example we focus on the new-minimal (12+12) off-shell version of simple four-dimensional supergravity obtained by tensoring the off-shell Yang-Mills multiplets (4+4,NL =1)and(3+0,NR =0). 

 
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