This page list all events and seminars that take place in the department this week. Please use the form below to choose a different week or date range.

OA/OT Seminar

Joint invariant subspaces on the polydisc and a commutant lifting theorem on the unit ball

Nov 19, 11:00—12:00, 2019, -101

Speaker

Jaydeb Sarkar (Indian Statistical Institute)

Abstract

In this talk we will discuss two central problems in multivariable operator theory: (1) joint invariant subspaces of the tuple of shift operators on the Hardy space over the unit polydisc, and (2) a commutant lifting theorem of the tuple of shift operator on certain analytic reproducing kernel Hilbert spaces over the unit ball. If time permits, we will also talk about Nevanlinna-Pick interpolation theorem and a relevant factorization result for multipliers on reproducing kernel Hilbert spaces over the unit ball.

Colloquium

On Benjamini-Schramm convergence

Nov 19, 14:30—15:30, 2019, Math -101

Speaker

Arie Levit (Yale)

Abstract

Benjamini-Schramm convergence is a probabilistic notion useful in studying the asymptotic behavior of sequences of metric spaces. The goal of this talk is to discuss this notion and some of its applications from various perspectives, e.g. for groups, graphs, hyperbolic manifolds and locally symmetric spaces, emphasizing the distinction between the hyperbolic rank-one case and the rigid high-rank case. Understanding the “sofic” part of the Benjamini-Schramm space, i.e. all limit points of “finitary” objects, will play an important role. From the group-theoretic perspective, I will talk about sofic groups, i.e. groups which admit a probabilistic finitary approximation, as well as a companion notion of permutation stability. Several results and open problems will be discussed.

אשנב למתמטיקה

משוואות אלגבריות, פירות, ופונקציות על שריגים

Nov 19, 16:10—17:30, 2019, אולם 101-

Speaker

דניאל דיסני

Abstract

לפירות שמקיימים את המשוואה בתמונה יש לפחות 80 ספרות. נראה איך ניתן למצוא אותם - באמצעות פונקציות מרוכבות על מרחב כל השריגים, וגיאומטריה של עקומים מעוקבים.

AGNT

DGAs with polynomial homology

Nov 20, 15:10—16:25, 2019, -101

Speaker

Haldun Özgür Bayindir (Haifa)

Abstract

Differential graded algebras(DGAs) are one of the most important objects of study in homological algebra. These are chain complexes with an associative and unital multiplication. Examples of DGAs include cochain complexes of topological spaces equipped with the cup product.

In this talk, I present our recent classification results on DGAs with polynomial homology. These results are obtained by exploiting interesting interactions between DGAs and stable homotopy theory. I am going to start my talk by stating these classification results. For the rest of the talk, I am going to present how stable homotopy theory comes into play for the classification of DGAs. This presentation is going to be accessible to a general audience.

BGU Probability and Ergodic Theory (PET) seminar

On the failure of Ornstein’s theory in the finitary category.

Nov 21, 11:10—12:00, 2019, -101

Speaker

Uriel Gabor (The Hebrew University)

Abstract

I’ll show the invalidity of finitary counterparts for three theorems in classification theory: The preservation of being a Bernoulli shift through factors, Sinai’s factor theorem, and the weak Pinsker property. This gives a negative answer to an old conjecture and to a recent open problem.


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