Tue, 16 May 2017

15:45 - 16:45
L4

Uniruling of symplectic quotients of coisotropic submanifolds

Tobias Sodoge
(UCL)
Abstract


Coisotropic submanifolds arise naturally in symplectic geometry as level sets of moment maps and in algebraic geometry in the context of normal crossing divisors. In examples, the Marsden-Weinstein quotient or (Fano) complete intersections are often uniruled. 
We show that under natural geometric assumptions on a coisotropic submanifold, the symplectic quotient of the coisotropic is always geometrically uniruled. 
I will explain how to assign a Lagrangian and a hypersurface to a fibered, stable coisotropic C. The Lagrangian inherits a fibre bundle structure from C, the hypersurface captures the generalised Reeb dynamics on C. To derive the result, we then adapt and apply techniques from Lagrangian Floer theory and symplectic field theory.
This is joint work with Jonny Evans.
 

Wed, 21 Jun 2017
15:00
S2.37

Post-Quantum Key Exchange from the LWE

Jintai Ding
(University of Cincinnati)
Abstract

In this lecture, we present  practical and provably
secure (authenticated) key exchange protocol and password
authenticated key exchange protocol, which are based on the
learning with errors problems. These protocols are conceptually
simple and have strong provable security properties.
This type of new constructions were started in 2011-2012.
These protocols are shown indeed practical.  We will explain
that all the existing LWE based key exchanges are variants
of this fundamental design.  In addition, we will explain
some issues with key reuse and how to use the signal function
invented for KE for authentication schemes.

Tue, 16 May 2017
14:00
L5

Random functions in Chebfun

Nick Trefethen
(Mathematical Institute)
Abstract

What's the continuous analog of randn?  In recent months I've been exploring such questions with Abdul-Lateef Haji-Ali and other members of the Chebfun team, and Chebfun now has commands randnfun, randnfun2, randnfunsphere, and randnfundisk.  These are based on finite Fourier series with random coefficients, and interesting questions arise in the "white noise" limit as the lengths of the series approaches infinity and as random ODEs become stochastic DEs.    This work is at an early stage and we are grateful for input from stochastic experts at Oxford and elsewhere.

Mathematicians, young and old, win awards, lots of them and Oxford mathematicians have their fair share. However, any university department is of course also home to a range of support staff whose job it is, on a good day, to enable academics to make the best use of their time.

Thu, 25 May 2017

14:00 - 15:00
L4

An efficient and high order accurate direct solution technique for variable coefficient elliptic partial differential equations

Prof. Adrianna Gillman
(Rice University)
Abstract

 

For many applications in science and engineering, the ability to efficiently and accurately approximate solutions to elliptic PDEs dictates what physical phenomena can be simulated numerically.  In this seminar, we present a high-order accurate discretization technique for variable coefficient PDEs with smooth coefficients.  The technique comes with a nested dissection inspired direct solver that scales linearly or nearly linearly with respect to the number of unknowns.  Unlike the application of nested dissection methods to classic discretization techniques, the constant prefactors do not grow with the order of the discretization.  The discretization is robust even for problems with highly oscillatory solutions.  For example, a problem 100 wavelengths in size can be solved to 9 digits of accuracy with 3.7 million unknowns on a desktop computer.  The precomputation of the direct solver takes 6 minutes on a desktop computer.  Then applying the computed solver takes 3 seconds.  The recent application of the algorithm to inverse media scattering also will be presented.
Fri, 26 May 2017

14:45 - 16:30
L2

The ultra-deep proteome - the dawn of the "Post-Proteomic Era

Dr Roman Fischer QBIOX Colloquium
(Target Discovery Institute University of Oxford)
Abstract

Proteomics is seen as the next logical step after genomics to understand life processes at the molecular level. With increasing capabilities of modern mass spectrometers the deep proteome (>8000 proteins detected) has become widely accessible, only to be replaced recently by the "Ultra-deep proteome" with ~14000 proteins detected in a single cell line. Furthermore, new data search algorithms and sample preparation methods allow not only to achieve comprehensive sequence coverage for the majority of proteins, but also to detect protein variations and single amino acid polymorphisms in proteins, further linking genomic variation to protein phenotypes. The combination of genomic and proteomic information on individual (patient) level could mark the beginning of the "Post-Proteomic Era".

Please register via https://www.eventbrite.co.uk/e/qbiox-colloquium-trinity-term-2017-ticke…

We all know there is no guaranteed way of beating the bank in a casino or predicting the tossing of a coin. Well maybe. Perhaps a little more thought and a large dose of mathematics could help optimise our strategies.

Thu, 18 May 2017
16:00
L6

The Zilber-Pink conjecture for Shimura varieties

Christopher Daw
(University of Reading)
Abstract

In 2016, Habegger and Pila published a proof of the Zilber-Pink conjecture for curves in abelian varieties (all defined over $\mathbb{Q}^{\rm alg}$). Their article also contained a proof of the same conjecture for a product of modular curves that was conditional on a strong arithmetic hypothesis. Both proofs were extensions of the Pila-Zannier strategy based in o-minimality that has yielded many results in this area. In this talk, we will explain our generalisation of the strategy to the Zilber-Pink conjecture for any Shimura variety. This is joint work with J. Ren.

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