# Events for November 30, 2017 from General and Seminar calendars

## Noncommutative Geometry Seminar

Time: 2:00PM - 3:00PM

Location: *BLOC 220*

Speaker: Ronghui Ji, IUPUI

Title: From relative amenability to relative soficity for countable groups

Abstract: We define a relative soficity for a countable group with respect to a family of subgroups. A group is sofic if and only if it is relatively sofic with respect to the family consisting of only the trivial subgroup. When a group is relatively amenable with respect to a family of subgroups, then it is relatively sofic with respect to the family. We show that if a group is relatively sofic with respect to a family of sofic subgroups, then the group is sofic. This in particular generalizes a result of Elek and Szabo. An example of relatively amenable group G with respect to an infinite family of subgroups F is constructed so that G is not relatively amenable with respect to any finite subfamily of F.

## Algebra and Combinatorics Seminar

Time: 2:45PM - 3:45PM

Location: BLOC 628

Speaker: Cesar Galindo, Universidad de los Andes

Title: Pointed finite tensor categories over abelian groups

Abstract: In this talk we will give a characterization of finite pointed tensor categories obtained as de-equivariantizations of finite-dimensional pointed Hopf algebras over abelian groups only in terms of the (cohomology class of the) associator of the pointed part. As an application, we will prove that every coradically graded pointed finite braided tensor category is a de-equivariantization of a finite dimensional pointed Hopf algebras over an abelian group. This talk is base on arXiv:1707.05230, joint work with Iván Angiono.

## Geometry Seminar

Time: 3:00PM - 4:00PM

Location: BLOC 220

Speaker: Patricio Gallardo , Washington University, St. Louis

Title: TBA