# Online activities 7-13 September 2020

Genoa Logic Seminar
Time: Tuesday, September 8, 17:00-18:00 CEST
Speaker: Gianluca Basso, Université de Lausanne
Title: Topological dynamics beyond Polish groups
Abstract: When $G$ is a Polish group, one way of knowing that it has “nice” dynamics is to show that $M(G)$, the universal minimal flow of $G$, is metrizable. For non-Polish groups, this is not the relevant dividing line: the universal minimal flow of $\mathrm{Sym}(\kappa)$ is the space of linear orders on $\kappa$—not a metrizable space, but still “nice”—, for example.
In this talk, we present a set of equivalent properties of topological groups which characterize having “nice” dynamics. We show that the class of groups satisfying such properties is closed under some topological operations and use this to compute the universal minimal flows of some concrete groups, like $\mathrm{Homeo}(\omega_{1})$. This is joint work with Andy Zucker.
Information: The seminar will take place on Microsoft Teams, at the page of the Genoa logic group. The access code is fpedcxn. Alternatively, you can write to camerlo@dima.unige.it to have an access link. Further information on the activities of the Genoa logic group can be found at http://www.dima.unige.it/~camerlo/glhome.html
Note: Due to the current emergency situation, the web page might not be updated.

CUNY Logic Seminar (MOPA)
Time: Wednesday, September 9, 3pm New York time (21:00 CEST) – note the time
Speaker: Saeideh Bahrami, Institute for Research in Fundamental Sciences, Tehran
Title: Fixed Points of Initial Self-Embeddings of Models of Arithmetic
Abstract: In 1973, Harvey Friedman proved his striking result on initial self-embeddings of countable nonstandard models of set theory and Peano arithmetic. In this talk, I will discuss my joint work with Ali Enayat focused on the fixed point set of initial self-embeddings of countable nonstandard models of arithmetic. Especially, I will survey the proof of some generalizations of well-known results on the fixed point set of automorphisms of countable recursively saturated models of PA, to results about the fixed point set of initial self-embeddings of countable nonstandard models of IΣ1.
Information: The seminar will take place virtually. Please email Victoria Gitman (vgitman@nylogic.org) for the meeting id.

Southern Illinois University Logic Seminar
Time: Thursday, 10 September, 1pm US Central Daylight Time (20:00 CEST)
Speaker: Mirna Džamonja (IHPST, CNRS-Université Panthéon-Sorbonne Paris, France)
Title: On logics that make a bridge from the Discrete to the Continuous
Abstract: We study logics which model the passage between an infinite sequence of finite models to an uncountable limiting object, such as is the case in the context of graphons. Of particular interest is the connection between the countable and the uncountable object that one obtains as the union versus the combinatorial limit of the same sequence.
Information: The seminar will take place virtually via zoom.