** "Geometry and Analysis on Groups" Research Seminar **

**Time:** 2017.12.05, 15:15–17:00

**Location:** Seminarraum 9, Oskar-Morgenstern-Platz 1, 2.Stock

**Title:** "Infinite symmetric group and combinatorial
cobordisms."

**Speaker:** Yurii Neretin
(Universität Wien)

**Abstract:**
It is known that for infinite-dimensional groups \(G\supset K\)
double coset spaces \(K\setminus G/K\) quite often admit natural multiplications
(which can be considered as degenerations of convolutions at
infinite-dimensional limits).
We consider the case when \(G\) is the product of 3 copies of
infinite symmetric group and \(K\) are subgroups in the diagonal
\(K_0\).
It will be explained that unitary representations of \(G\) generate in a natural way representations of certain category, whose morphisms are triangulated two-dimensional surfaces with special colorings and product of morphisms is similar to concatenation of cobordisms.