Activities This Week
BGU Probability and Ergodic Theory (PET) seminar
Operator ergodic theorems
Oct 31, 11:00—12:00, 2017, 201
Speaker
Michael Lin (BGU)
Abstract
See attached file. This will be the first in a series of survey talks:
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Operator ergodic theorems.
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Ergodic and mixing theorems for Markov operators (discrete time Markov processes).
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Ergodic theorems for random walks on locally compact groups (convolution powers). The second talk will focus on the results needed for the third one.
Colloquium
TBA
Oct 31, 14:30—15:30, 2017, Math -101
Speaker
Faculty Meeting (no colloquium)
Algebraic Geometry and Number Theory
Foliations on unitary Shimura varieties in positive characteristic
Nov 1, 15:10—16:30, 2017, Math -101
Speaker
Ehud de Shalit (Hebrew University )
Abstract
Let E be a quadratic imaginary field and p a prime which is inert in E. Let S be the special fiber (at p) of a unitary Shimura variety of signature (n,m) and hyperspecial level subgroup at p, associated with E/Q.
We study a natural foliation in the tangent bundle of S, which is originally defined on the \mu-ordinary stratum only, but is extended to a certain non-singular blow-up of S. We identify the quotient of S by the foliation with a certain irreducible component of a Shimura variety with parahoric level structure at p. As a result we get new results on the singularities of the latter.
We study integral submanifolds of the foliation and end the talk with a new conjecture of Andre-Oort type.
Geometry and Group Theory
From one-sided shifts to compact generation of groups
Nov 5, 14:30—15:30, 2017, -101
Speaker
Waltraud Lederle (BGU)
Abstract
Hiroki Matui defined the concept of the topological group of an étale groupoid. In the case where the groupoid comes from a one-sided shift of finite type, he proved that the associated topological full group is finitely generated. We will show how to re-interpret these groups as tree almost automorphism groups and thus obtain compactly generated groups almost acting on trees.