Seminars

Upcoming seminars can also be found here.
2020 Jul 13

Combinatorics: Edinah K. Gnang (JHU)

2:00pm to 4:00pm

Location: 

Zoom
Speaker: Edinah K. Gnang (JHU)
Title: On the Kotzig-Ringel-Rosa conjecture
Abstract:
In this talk we describe and motivate the K.R.R. conjecture and describe a functional graph theoretic approach enabling us to tackle the K.R.R. conjecture via a composition lemma.
2020 Jul 06

Combinatorics: Xinyu Wu (CMU)

2:00pm to 4:00pm


Speaker: Xinyu Wu (CMU)
Title: Explicit near-fully X-Ramanujan graphs
Abstract:
In this talk I will introduce constructions of finite graphs which resemble some given infinite graph both in terms of their local neighborhoods, and also their spectrum.
2020 Jun 24

Logic Seminar - Jorge Cely

11:00am to 1:00pm

Location: 

Zoom - ID: 995 8999 9308 Password: 568039
Jorge Cely will speak about the fundamental lemma for spherical Hecke algebras and motivic integration.
 

Abstract:
2020 Jun 23

Dalia Terhesiu (Leiden) Mixing rates for Infinite horizon Lorentz maps

2:00pm to 3:00pm

Abstract: I will report on recent results on sharp error rates in the local limit theorem for the Sinai billiard map (one and two dimensional) with infinite horizon. This is joint work with F. Pene. This result allows to also obtain higher order terms and thus, sharp mixing rates in the speed of mixing of dynamically Hölder observables for the planar and tubular infinite horizon Lorentz gases in the map (discrete time) case.

Join Zoom Meeting
Meeting ID: 917 3652 5930
Password: 7m913h
2020 Jun 16

John Griesmer (Colorado School of Mines) Separating Bohr denseness from measurable recurrence

2:00pm to 3:00pm

Abstract: We construct a set which is dense in the Bohr topology on the group of integers and which is not a set of measurable recurrence, answering a question asked by Bergelson, Hegyvári, Ruzsa, and the author, in various combinations.  This talk will provide a broad overview and explain details of the construction. We will see similarities to many other examples in additive combinatorics and ergodic theory, such as Igor Kriz's construction showing topological recurrence does not imply measurable recurrence, and Ruzsa's niveau sets.
2020 Jun 10

Logic Seminar - Kobi Peterzil

11:00am to 1:00pm

Location: 

Zoom - ID: 951 5522 0236 Password: 387201

Kobi Peterzil will speak about the infinitesimal subgroup of a simple real Lie group.
(w. Martin Bays)


Abstrract:

A theorem with Pillay and Starchenko (2000) says that If G is a simple linear Lie group then the pure group (G,.) is either:

(i) unstable, and then bi-interpretable with the real field, e.g when G is compact,
or
(ii) stable, and then bi-interpretable with the complex field.
2020 Jun 09

Weikun He (HUJI), Equidistribution of linear random walks on the torus.

2:00pm to 3:00pm


Abstract: Quantitative equidistribution for linear random walks on the torus was first obtained by Bourgain, Furman, Lindenstrauss and Mozes. In this talk I will present a recent progress where the proximality assumption in their result is relaxed. I will also discuss an application to expansion in groups. This is based on a joint work with Nicolas de Saxcé.

Link: https://huji.cloud.panopto.eu/Panopto/Pages/Viewer.aspx?id=3c855e5a-44bf...
2020 Jun 24

Analysis Seminar: Angkana Rüland (Heidelberg) "Microstructure in Shape-Memory Alloys: Rigidity, Flexibility and Some Numerical Simulations"

12:00pm to 1:00pm

Location: 

zoom

Title: Microstructure in Shape-Memory Alloys: Rigidity,Flexibility and Some Numerical Simulations

 

Abstract: In this talk I will discuss a striking dichotomy whichoccurs in the mathematical analysis of microstructures in shape-memory alloys:On the one hand, some models for these materials display a very rigid structurewith only very specific microstructures, if one assumes that surface energiesare penalised. On the other hand, without this penalisation, for the samemodels a plethora of very ``wild'' solutions exists.

2020 Jun 22

Combinatorics: Lukas Kuhne (HUJI)

11:00am to 1:00pm


Speaker: Lukas Kuhne (HUJI)

Title:  Matroids doing Algebra

Abstract:

A matroid  is a combinatorial object based on an abstraction of linear independence in vector spaces and forests in graphs. It is a classical question to determine whether a given matroid is representable as a vector configuration over a field. Such a matroid is called linear.
2020 May 25

Combinatorics: Yuval Flimus (Technion)

11:00am to 1:00pm

Speaker: Yuval Flimus (Technion)


Title: Oligarchy testing

Abstract:
Arrow's impossibility theorem states that the only voting rule satisfying certain natural requirements is a dictatorship.
Gil Kalai showed that even if we relax some of these requirements so that they only hold with high probability, we are not getting genuine new voting rules.
Arrow's theorem is just one of many paradoxes in social choice theory.
2020 May 26

Jon Aaronson (TAU) On mixing properties of infinite measure preserving transformations

2:00pm to 3:00pm

Abstract: I'll discuss  various  "ratio mixing"  properties
of transformations preserving infinite measures e.g. "Krickeberg mixing" (based on the example in Hopf's 1936 book) & "rational weak mixing". I'll also introduce a new one connected to "tied down" renewal theory.

Contains joint works with Hitoshi Nakada, Dalia Terhesiu & Toru Sera


Join Zoom Meeting

Meeting ID: 944 0148 4601
Password: 8w24u0
2020 May 20

Logic Seminar - Hind Abu Saleh "Reducts of the Real Ordered Field and Strongly Bounded Structures"

12:00pm to 2:00pm

Location: 

Zoom: Meeting ID: 928 6821 1553 Password: 829281
Hind Abu Saleh will speal about reducts of the real ordered field and strongly bounded structures.
.
Title: Reducts of the Real Ordered Field and Strongly Bounded Structures

Abstract: Let N =〈 A ;<,.. 〉 be an o-minimal structure and let A =〈 A ;.. 〉 be a reduct of N . The structure A is called strongly bounded if every A -definable subset of A is either bounded or co-bounded. In this talk we examine additive strongly bounded structures over R and as a corollary we identify all possible reducts of 〈 R ;+, ⋅ ,< 〉 , which expand the vector space

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