Fridays@4

Please note that the list below only shows forthcoming events, which may not include regular events that have not yet been entered for the forthcoming term. Please see the past events page for a list of all seminar series that the department has on offer.

Past events in this series
Tomorrow
16:00
Abstract

In this session we discuss techniques to get the most out of your supervision sessions and tips on how to work with different personalities and use your supervisor's skills to your advantage. The session will be run by DPhil students and discussion among students during the session is encouraged.  

The join button will be published on the right (Above the view all button) 30 minutes before the seminar starts (login required).

6 November 2020
16:00
Agnese Barbensi and Wolfger Peelaers
Abstract
Agnese Barbensi
Title: Knotted biopolymers
Abstract: Many biopolymers -most notably DNA- are knotted, or present some entanglement phenomena. The geometry and topology of these biopolymers has profound effects on their functioning. Using tools coming from topology and knot theory can help understanding the relations between the spatial arrangement and the behaviour of these molecules. In this talk we will give a brief overview of some useful techniques and recent work in this area. 
 
Wolfger Peelaers
Title: Vertex operator algebraic structures in quantum field theory
Abstract: Quantum field theory was originally developed to address questions involving interacting elementary particles, but ever since it has also provided, time and again, a bridge between ideas, concepts, and structures in mathematics and observables in physics. In this talk I will describe a remarkable connection of that type between vertex operator algebras and a class of highly symmetrical quantum field theories.

The join button will be published on the right (Above the view all button) 30 minutes before the seminar starts (login required).

20 November 2020
16:00
Yuji Nakatsukasa
Abstract

In this new session a speaker tells us about how their area of mathematics can be used in different applications.

In this talk, Yuji Nakatsukasa tells us about how random matrix theory can be used in numerical linear algebra. 

 

Abstract

Randomized SVD is a topic in numerical linear algebra that draws heavily from random matrix theory. It has become an extremely successful approach for efficiently computing a low-rank approximation of matrices. In particular the paper by Halko, Martinsson, and Tropp (SIREV 2011) contains extensive analysis, and has made it a very popular method. The classical Nystrom method is much faster, but only applicable to positive semidefinite matrices. This work studies a generalization of Nystrom's method applicable to general matrices, and shows that (i) it has near-optimal approximation quality comparable to competing methods, (ii) the computational cost is the near-optimal O(mnlog n+r^3) for a rank-r approximation of dense mxn matrices, and (iii) crucially, it can be implemented in a numerically stable fashion despite the presence of an ill-conditioned pseudoinverse. Numerical experiments illustrate that generalized Nystrom can significantly outperform state-of-the-art methods. In this talk I will highlight the crucial role played by a classical result in random matrix theory, namely the Marchenko-Pastur law, and also briefly mention its other applications in least-squares problems and compressed sensing.

The join button will be published on the right (Above the view all button) 30 minutes before the seminar starts (login required).

27 November 2020
16:00
Abstract

In this session we will discuss how interviewing and being interviewed has changed now that interviews are conducted online. We will have a panel comprising those who have experienced being interviewed online and those who have interviewed online and we will compare experiences with in-person interviews. 

The join button will be published on the right (Above the view all button) 30 minutes before the seminar starts (login required).

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