Algèbre et géométrie

14.00 - 14.45 : Naomi Andrew (Laboratoire de Mathématiques d'Orsay)Title: Automorphisms behaving badlyAbstract: Baumslag–Solitar groups are HNN extensions of the infinite cyclic group, whose isomorphism type is controlled by two integers giving the two embeddings. They have provided many counterexamples over the years: for example, they include groups which are not Hopfian and groups which are Hopfian but not residually finite. Later, Collins and Levin showed that there are Baumslag–Solitar groups that do not have finitely generated automorphism group. Moving this construction to higher rank, one can study "Leary–Minasyan groups": these are […]