[Binghamton Geometry/Topology Seminar] Seminar

[Ross Geoghegan]

                   BINGHAMTON GEOMETRY/TOPOLOGY SEMINAR


   Date: Thursday October 6, 2005

   Time:  2.50 pm

   Place: Library North 2205 followed by coffee/tea in the Anderson
          Reading Room.

   Speaker: Qin Lu (Lafayette College) 

   Title: A study of L-2 Betti numbers and Bianchi Groups 

Abstract: 
In general, calculating L-2 Betti numbers of an infinite
group is very complicated, while calculating L-2 Betti numbers of a
finite group is very easy. Bianchi groups are subgroups of PSL_2(C)
and they are amalgamated products and HNN extensions of infinite cyclic
and some finite groups( Z/2,Z/3, D_2, S_3, A_4). Bianchi groups act
on Mendoza complex with finite CW complex. The cohomology of Bianchi
groups is calculated through this action. Recently, L-2 Betti numbers
of other infinite groups such as Right-angled Coxeter groups have been
calculated. I hope to develop some method to calculate the L-2 Betti
numbers of Bianchi groups. At this stage, I am still exploring. Hence,
this talk is a study note as introduction to L-2 Betti numbers and
Bianchi groups.


NOTE:  The seminar has a webpage where the semester's program is listed:

http://math.binghamton.edu/MATH/dept/topsem/index.html

It can also be linked from the Department's Home Page.
_____________________
IF YOU WANT TO BE REMOVED FROM THIS EMAIL LIST WRITE
ross at math.binghamton.edu
:x