Seminar series
Date
Wed, 22 Jun 2011
Time
16:00 -
17:00
Location
SR1
Speaker
Moritz Rodenhausen
Organisation
Rheinische Friedrich-Wilhelms-Universität Bonn
In euclidean space there is a well-known parallelogram law relating the
length of vectors a, b, a+b and a-b. In the talk I give a similar formula
for translation lengths of isometries of CAT(0)-spaces. Given an action of
the automorphism group of a free product on a CAT(0)-space, I show that
certain elements can only act by zero translation length. In comparison to
other well-known actions this leads to restrictions about homomorphisms of
these groups to other groups, e.g. mapping class groups.