GENERAL
SEMINAR

“Dehn
twists, commutators, and bounded cohomology”

by

MUSTAFA
KORKMAZ

(METU)

Abstract: For an element $x$ of a group $[G,G]$, the commutator length $cl(x)$ of $x$
is defined as the minimal number $s$ such that $x$ can be written as a product
of $s$ commutators. The stable commutator
length $scl(x)$ of $x$ is the limit of $cl(x^n)/n$. I will discuss these
notions for Dehn twists on a surface. There is also
the notion of bounded cohomology. After introducing
these two seemingly unrelated concepts, I will discuss the relation between
them for the mapping class group of a surface.

Date : April 25, 2012 (Wednesday)

Time : 15.40-16.30

Place: Bilkent University
,Mathematics Seminar Room SA141

Tea and cookies will be served before the seminar.