"Geometry and Analysis on Groups" Research Seminar

Time: 2017.10.10, 15:15–17:00
Location: Seminarraum 9, Oskar-Morgenstern-Platz 1, 2.Stock
Title: "Jewels in Outer space."
Speaker: Karen Vogtmann (University of Warwick)
Abstract: Outer space is a contractible space with a proper action by the group $$\mathrm{Out}(F_n)$$ of outer automorphisms of a free group. It is naturally divided into open simplices. By truncating appropriate faces of these simplices one obtains compact polytopes ("jewels"), and the union of these polytopes is an equivariant deformation retract of Outer space with compact quotient. We show that this retract is homeomorphic to the Bestvina-Feighn bordification of Outer space, and identify the boundary. This is joint work with Kai-Uwe Bux and Peter Smillie.