Jonathan Hillman (University of Sydney)

Friday 18th April, 12.05-12.55pm, Carslaw 373

Finite index endomorphisms of mapping tori of free group automorphisms

A group G is hopfian if every onto endomorphism f:G->G is an isomorphism. We shall describe some extensions of this notion, and examine the case of semidirect products G=F(r) \rtimes_\phi Z, where \phi is an automorphism of the free group F(r). (Such groups G are the "mapping tori" of the title.) Although these notions derive from topology, the arguments are primarily algebraic.

This is based on joint work with M.Bridson, D.Groves and G.Martin.