To participate in this seminar, please register here: https://www.msri.org/seminars/25206

Abstract: This is work in progress, joint with Nick Ramsey (UCLA).

A conjecture, now disproved by Chernikov, Hrushovski, Kruckman, Krupinski, Pillay and Ramsey, asked whether any group with a simple theory is definably amenable. It is well known that the counting measure on finite fields gives rise to a non-standard counting measure on pseudo-finite fields (the infinite models of the theory of finite fields). It was unknown whether other PAC fields possessed a reasonable measure, and in this talk, we will show that some of them do, although the measure we define does not have all the nice properties of a counting measure when the field is not pseudo-finite.  This result can be used to show that if G is a group definable in an e-free perfect PAC field, then G is definably amenable.

We hope to extend our results to the wider class of bounded perfect PAC fields.

To attend this seminar, please register here: https://www.msri.org/seminars/25205

Abstract: Culler, Morgan, and Shalen pioneered the detection essential surfaces in 3-manifolds through SL(2,C) character varieties. I’ll discuss how symmetries of the 3-manifold affect this detection, concluding with some examples. This is joint work with Jay Leach.

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

Tea for members and participants of the Random and Arithmetic Structures in Topology program.

To participate, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

Abstract:

We shall consider sections of (products of) elliptic schemes, and their "torsion values". For instance, what can be said
of the complex numbers b for which (2, \sqrt{2(2-b)}) is torsion on y^2=x(x-1)(x-b)?
In particular, we shall recall results of "Manin-Mumford type" and illustrate some applications to elliptical billiards. Finally, we shall frame these issues as special cases of a general question in arithmetic dynamics, which can be treated with different methods, depending on the context.

(Most results refer to work with Pietro Corvaja and David Masser.)

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

Abstract: We prove that a harmonic quasi-isometric map between two pinched Hadamard surfaces is a quasi-conformal diffeomorphism, thus generalizing a theorem of Schoen-Yau. This is a joint work with Yves Benoist.

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

This is one of the research seminars for the RAS program, that distinguishes itself from the postdocs and program associates seminars in that speakers are chosen among Research Members, Research Professors with occasional outside speakers.

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To attend this event, please register here: https://www.msri.org/seminars/25205

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

Valuation theory plays a major part in the interaction between number theory and logic. In this seminar, a variety of topics from valuation theory, and in particular connections to model theory, will be discussed. There will be a strong emphasis on results involving the definability of valuations.

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this event, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To attend this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To attend this seminar, please register here: https://www.msri.org/seminars/25205

Tea for members and participants of the Decidability, definability and computability in number theory virtual program.

To participate, please register here: https://www.msri.org/seminars/25206

To attend this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25205

This is one of the research seminars for the RAS program, that distinguishes itself from the postdocs and program associates seminars in that speakers are chosen among Research Members, Research Professors with occasional outside speakers.

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To attend this event, please register here: https://www.msri.org/seminars/25205

The PA seminar is a learning seminar for early career mathematicians (graduate student and postdocs).  Please only join the seminar if you are an early career mathematician.

To participate, please email Tommaso Cremaschi or James Farre.

Valuation theory plays a major part in the interaction between number theory and logic. In this seminar, a variety of topics from valuation theory, and in particular connections to model theory, will be discussed. There will be a strong emphasis on results involving the definability of valuations.

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this event, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To attend this seminar, please register here: https://www.msri.org/seminars/25205

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

To participate in this seminar, please register here: https://www.msri.org/seminars/25206