Mathematics Colloquium

Wednesday, September 13, 1995, 4:00pm

Professor Hyman Bass

Columbia University

speaks on

TREE LATTICES

Abstract: The group $G$ of automorphisms of a locally finite tree $X$ is a locally compact group, so one can consider lattices $L$ in $G$, i.e. discrete subgroups with quotient $G/L$ that is compact, or, more generally, of finite invariant volume. These are called also $X$-lattices. Natural examples arise in non archimedean Lie groups, such as $H = SL(2,F)$, where $F$ is say a $p$-adic field. There is a natural ``Bruhat-Tits" tree $X$ on which $H$ operates, so lattices in $H$ will also be $X$-lattices. The lecture discusses the theory of general tree lattices, comparing it with the Lie group case.

Tea: High tea will be served at 3:30pm in the Lounge.

Emmy's: Certain refreshments will be available at the Emmy's after the talk.

Host(ess): Dorothy Wallace will be the hostess, anybody interested in having dinner with the speaker should contact Dorothy.