פעילויות השבוע
BGU Probability and Ergodic Theory (PET) seminar
Amenability, proximality, and higher order syndeticity Online
ינו 7, 11:10—12:00, 2021, Online
מרצה
Guy Salomon (Weizmann Institute)
תקציר
An action of a discrete group G on a compact Hausdorff space X is called proximal if for every two points x and y of X there is a net g_i in G such that lim(g_i x)=lim(g_i y), and strongly proximal if the action of G on the space Prob(X) of probability measures on X is proximal. The group G is called strongly amenable if all of its proximal actions have a fixed point and amenable if all of its strongly proximal actions have a fixed point.
In this talk, I will present a correspondence between (strongly) proximal actions of G and Boolean algebras of subsets of G consisting of certain kinds of “large” subsets. I will use these Boolean algebras to establish new characterizations of amenability and strong amenability. Furthermore, I will show how this machinery helps to characterize “dense orbit sets” answering a question of Glasner, Tsankov, Weiss, and Zucker.
This is joint work with Matthew Kennedy and Sven Raum.
Jerusalem - Be'er Sheva Algebraic Geometry Seminar
The Langlands-Rapoport Conjecture for global G-shtukas
ינו 13, 15:00—16:30, 2021,
מרצה
Urs Hartl (Münster)
תקציר
Moduli spaces for bounded global G-shtukas are function field analogs of Shimura varieties. The Langlands-Rapoport conjecture wants to give a group theoretic description of their points with values in finite fields.