TOPOLOGY SEMINAR

**"****Periodic Maps on Simply
Connected 4-Manifolds****"**

By

**Abstract: **It is known that
simply connected, closed, 4-manifolds are classified in terms of intersection
pairing and Kirby-Siebenman invariant. In the non-simply connected case, since
the fundamental group acts freely on the universal cover, classification of
these concern the topological classification of free periodic maps on simply
connected 4-manifolds. In general, a periodic map is allowed to have fixed
points or periodic points of period smaller than the map period. When this happens
the quotient space has singularities, which is an orbifold. In the case of
isolated singularities one can still classify periodic maps by some invariants associated
to this orbifold. The aim of this talk is to give some overview of the homotopy
types of pseudofree actions and to present the above mentioned invariants in
the orbit category setting. This is an ongoing work with M. Pamuk.

**Date: ****Monday, November 9, 2015**

**Time: ****13.40 – 14:30**

**Place: ****Mathematics Seminar Room,
SA-141**

**All are most cordially invited.
Tea and cookies will be served after the talk.**