# Events for 02/03/2021 from all calendars

## Student/Postdoc Working Geometry Seminar

**Time: ** 10:00AM - 11:00AM

**Location: ** zoom

**Speaker: **P. Buergisser, TU Berlin

**Title: ***TBA*

## Groups and Dynamics Seminar

**Time: ** 12:00PM - 1:00PM

**Location: ** online

**Speaker: **Alina Vdovina, Newcastle University, UK

**Title: ***Buildings, C*-algebras and new higher-dimensional analogues of the Thompson groups*

**Abstract: **We present explicit constructions of infinite families of CW-complexes of arbitrary dimension with buildings as the universal covers. These complexes give rise to new families of C*-algebras, classifiable by their K-theory.
The underlying building structure allows explicit computation of the K-theory. We will also present new higher-dimensional generalizations of the Thompson groups, which are usually difficult to distinguish, but the K-theory of C*-algebras gives new invariants to recognize non-isomophic groups.

## Topology Seminar

**Time: ** 4:00PM - 5:00PM

**Location: ** Zoom

**Speaker: **Mohammad Farajzadeh Tehrani, University of Iowa

**Title: ***Relative Seiberg-Witten invariants and a Sum Formula*

**Abstract: **I will introduce relative Seiberg-Witten (or SW) moduli spaces for an arbitrary pair (X,S) of a closed oriented 4-manifold X and a closed oriented 2-dimensional submanifold S in X with positive genus. Using these moduli spaces, we obtain an SW sum formula (aka a product formula) that relates the SW invariants of a sum X of two closed oriented 4-manifolds X1 and X2 along a common oriented surface S with dual self-intersections to the relative SW invariants of (X1,S) and (X2,S).
This formula generalizes Morgan-Szabo-Taubes' product formula. This is joint work with Pedram Safari.