View Single Post
Bacle
#1
Dec5-10, 01:51 AM
P: 662
Hi, everyone:

I am trying to understand why the mapping class group of the
torus T^2 (i.e., the group of orientation-preserving self-
diffeomorphisms, up to isotopy) is (iso. to) Gl(2,Z) ( I just
realized this is the name of the group of orientation-preserving
automorphisms). Anyone know what the connection is, between these
two.(or, even better, a proof, or ref. for a proof.)? .
All I can think off is that there may be some connection
with the fact that Pi_1(T^2)=Z(+)Z , but that is all I have.

Thanks for any Ideas.
Phys.Org News Partner Science news on Phys.org
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100