Tue, 17 May 2016

10:00 - 11:00
C1

Number theory tools for Cryptographic Applications

Giacomo Micheli
(Oxford University)
Abstract

In this lecture we describe the effective Chebotarev Theorem for global function fields and show how this can be used to describe the statistics of a polynomial map f in terms of its monodromy groups. With this tool in hand, we will provide a strategy to remove the remaining heuristic in the quasi-polynomial time algorithm for discrete
logarithm problems over finite fields of small characteristic.

Wed, 11 May 2016

16:00 - 17:00
C1

Commutator Subgroup and Quasimorphisms

Nicolaus Heuer
(Oxford)
Abstract

Quasimorphisms (QM) of groups to the reals are well studied and are linked to stable commutator length (scl) via Bavard Duality- Theorem. The notion of QM can be generalized to yield maps  between groups such that each QM from one group pulls back to a QM in the other.

We will give both a short overview of features of scl and investigate these generalized QMs with large scale properties of the commutator group. 

Wed, 04 May 2016

16:00 - 17:00
C1

Classifying Groups up to Quasi-Isometry

Alex Margolis
Abstract

In his ICM address in 1983, Gromov proposed a program of classifying finitely generated groups up to quasi-isometry. One way of approaching this is by breaking a group down into simpler parts by means of a JSJ decomposition. I will give a survey of various JSJ theories and related quasi-isometric rigidity results, including recent work by Cashen and Martin.

Wed, 27 Apr 2016

16:00 - 17:00
C1

Random walks, harmonic functions and Poisson boundary

Vigolo Federico
(Oxford)
Abstract

in this talk I will try to introduce some key ideas and concepts about random walks on discrete spaces, with special interest on random walks on Cayley graphs.

Mon, 29 Feb 2016
16:30
C1

Torelli and Borel-Tits theorems via trichotomy

Carlos Alfonso Ruiz Guido
(Oxford University)
Abstract

Using the "trichotomy principle" by Boris Zilber I will give model theoretic proofs of appropriate versions of Torelli theorem and Borel-Tits theorem. The first one has interesting applications to anabelian geometry, I won't assume any prior knowledge in model theory.

Fri, 11 Mar 2016

11:00 - 12:00
C1

On the birational invariance of the BCOV torsion of Calabi-Yau threefold (joint with V. Maillot)

Damian Rössler
(Oxford)
Abstract

Fang, Lu and Yoshikawa conjectured a few years ago that a certain string-theoretic invariant (originally introduced by the physicists M. Bershadsky, S. Cecotti, H. Ooguri, and C. Vafa) of Calabi-Yau threefolds is a birational invariant. This conjecture can be viewed as a "secondary" analog (in dimension three) of the birational invariance of Hodge numbers of Calabi-Yau varieties established by Batyrev and Kontsevich. Using the arithmetic Riemann-Roch theorem, we prove a weak form of this conjecture. 

Fri, 04 Mar 2016

11:00 - 12:00
C1

TBA

Minhyong Kim
Fri, 26 Feb 2016

11:00 - 12:00
C1

TBA

Jennifer Balakrishnan
Fri, 19 Feb 2016

11:00 - 12:00
C1

\zeta(3) in graviton-graviton scattering and the moduli space of CY manifolds

Philip Candelas
(Oxford)
Abstract

I will discuss how \zeta(3) occurs in quantum corrections to the Einstein action, and how this causes \zeta(3) to be seen in the moduli space of CY manifolds. I will also draw attention to the fact that the dependence of the moduli space on \zeta(3) has a p-adic analogue.

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