"Geometry and Analysis on Groups" Research Seminar
Time: , 15:00–17:00
Location: Seminarraum 9, Oskar-Morgenstern-Platz 1, 2.Stock
Title: Groups acting on trees
Speaker: Alexandre Martin
Introductory part: basics of groups acting on trees, and Bass-Serre just
in the case of amalgamated products: construction of the group in term
of cosets, and reconstruction of the group out of the action. Main
example: pi_1 of the genus 2 surface as an amalgamation of free groups
(van Kampen).
"Abstract":
how to use the action on the tree to
understand the structure of the group: torsionfree-ness, existence of
free subgroups and nonsimplicity.