Eventss

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 24

Amitsur Memorial Symposium 2020 (on Zoom)

(All day)

Location: 

Zoom

The Amitsur Memorial Symposium is an annual conference in memory of Prof. Shimshon Avraham Amitsur. It is hosted by a different institution each year since 1995.

The 27th Amitsur Memorial Symposium was originally planned to take place on the grounds of the Open University of Israel in Raanana. Instead, due to the COVID-19 pandemic, it will be held online on June 24th and 25th, 17:00–20:30

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 Jun 04

מפגשי מתעניינים לתואר שני

Lecturer: 

Prof. Michael Hochman ; Orna Barak
11:00am

Location: 

Zoom
חושבים על תואר שני? מתלבטים על מסלול כלשהו? רוצים לדעת יותר, מה זה בכלל אומר ללמוד כאן לתואר שני?
אז אל דאגה, אנחנו יודעים שיש הרבה שאלות. לכן ריכזנו במיוחד עבורך את כל מפגשי המתעניינים שלנו בזום, סביב המסלולים השונים והחוגים.
 
מפגשי התעניינות ב-ZOOM לתואר שני במתמטיקה יהיו:
ב-3.6.2020 בשעה 14:00
ב-4.6.2020 בשעה 11:00
נשמח לראותך!
2020 Jun 03

מפגשי מתעניינים לתואר שני

Lecturer: 

Prof. Michael Hochman ; Orna Barak
2:00pm

Location: 

Zoom
חושבים על תואר שני? מתלבטים על מסלול כלשהו? רוצים לדעת יותר, מה זה בכלל אומר ללמוד כאן לתואר שני?
אז אל דאגה, אנחנו יודעים שיש הרבה שאלות. לכן ריכזנו במיוחד עבורך את כל מפגשי המתעניינים שלנו בזום, סביב המסלולים השונים והחוגים.
 
מפגשי התעניינות ב-ZOOM לתואר שני במתמטיקה יהיו:
ב-3.6.2020 בשעה 14:00
ב-4.6.2020 בשעה 11:00
נשמח לראותך!
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
2020 May 28

Basic Notions: Michael Tenkin "Resolution: classical, relative and weighted"

4:00pm to 5:15pm

Location: 

Join Zoom Meeting https://huji.zoom.us/j/98768675115?pwd=WnZOZUpuVmpoNGkrYWQxanNVWkQzUT09,

Until recently there was known an essentially unique way to resolve singularities of varieties of 
characteristic zero in a canonical way (though there were different descriptions and proofs of correctness). 
Recently a few advances happened -- 
1) The algorithm was extended to varieties with log structures and even to morphisms -- This requires to consider 
more general logarithmic blow ups and results in a stronger logarithmic canonicity of the algorithms even for resolution 

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