Thu, 06 Oct 2022
14:00
N3.12

Gravitational Regge bounds

Kelian Haring
(Cern)

Note: we would recommend to join the meeting using the Zoom client for best user experience.

Further Information

It is possible to join online via Zoom.

Abstract

I will review the basic assumptions and spell out the arguments that lead to the bound on the Regge growth of gravitational scattering amplitudes. I will discuss the Regge bounds both at fixed transfer momentum and smeared over it. Our basic conclusion is that gravitational scattering amplitudes admit dispersion relations with two subtractions. For a sub-class of smeared amplitudes, black hole formation reduces the number of subtractions to one. Finally, I will discuss bounds on local growth derived using dispersion relations. This talk is based on https://arxiv.org/abs/2202.08280.

Wed, 05 Oct 2022
17:00
Lecture Theatre 1, Mathematical Institute, Radcliffe Observatory Quarter, Woodstock Road, OX2 6GG

The million-dollar shuffle: symmetry and complexity - Colva Roney-Dougal

Colva Roney-Dougal
(University of St Andrews)
Further Information

In 1936, Alan Turing proved the startling result that not all mathematical problems can be solved algorithmically. For those which can be, we still do not always know when there's a clever technique which could give us the answer quickly. In particular, the famous "P = NP" question asks whether, for problems where the correct solution has a proof which can easily be checked, in fact there's a quick way to find the answer.

Many difficult problems become easier if they have symmetries: finding the shortest route to deliver many parcels would be easy if all the houses were neatly arranged in a circle. This lecture will explore the interactions between symmetry and complexity.

Colva Roney-Dougal is Professor of Pure Mathematics at the University of St Andrews and Director of the Centre for Interdisciplinary Research in Computational Algebra.

Please email @email to register.

The lecture will be available on our Oxford Mathematics YouTube Channel on 12 October at 5 pm.

The Oxford Mathematics Public Lectures are generously supported by XTX Markets.

MSGNN: a spectral graph neural network based on a novel magnetic signed Laplacian
He, Y Permultter, M Reinert, G Cucuringu, M Proceedings of the First Learning on Graphs Conference (LoG 2022) 40:1-40:39 (21 Dec 2022)
Tue, 22 Nov 2022
14:00
L6

Character sheaves and Khovanov-Rozansky homology

Kostiantyn Tolmachov
(Edinburgh University)
Abstract

Khovanov-Rozansky homology is a link invariant that categorifies the HOMFLY-PT polynomial. I will describe a geometric model for this invariant, living in the monodromic Hecke category. I will also explain how it allows to identify objects representing graded pieces of Khovanov-Rozansky homology, using a remarkable family of character sheaves. Based on joint works with Roman Bezrukavnikov.

The impact of repeated rapid test strategies on the effectiveness of at-home antiviral treatments for SARS-CoV-2
Menkir, T Donnelly, C Nature Communications volume 13 issue 1 5283 (08 Sep 2022)
Moving beyond landscape resistance: considerations for the future of connectivity modelling and conservation science
Unnithan Kumar, S Turnbull, J Hartman Davies, O Hodgetts, T Cushman, S Landscape Ecology volume 37 2465-2480 (13 Aug 2022)
A unified construction for series representations and finite approximations of completely random measures
Lee, J Miscouridou, X Caron, F Bernoulli volume 29 issue 3 2142-2166 (27 Apr 2023)
Polynomial bounds for chromatic number. I. Excluding a biclique and an induced tree
Scott, A Seymour, P Spirkl, S Journal of Graph Theory volume 102 issue 3 458-471 (01 Mar 2023)
Fri, 25 Nov 2022

12:00 - 13:00
N3.12

Knutson's Conjecture on the Representation Ring

Diego Martin Duro
(University of Warwick)
Abstract

Donald Knutson proposed the conjecture, later disproven and refined by Savitskii, that for every irreducible character of a finite group, there existed a virtual character such their tensor product was the regular character. In this talk, we disprove both this conjecture and its refinement. We then introduce the Knutson Index as a measure of the failure of Knutson's Conjecture and discuss its algebraic properties.

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