Buildings, Group Extensions and the Cohomology of Congruence Subgroups 
by Alejandro Adem 


KEYWORDS 
        cohomology of groups, arithmetic groups 
DATE 
        February 20, 1997 
STATUS 
        Preprint 
COMMENT 



Abstract

We use buildings and group extensions to compute lower bounds on the top 
betti numbers for the cohomlogy of the level p congruence subgroups of 
SL(3,Z) and Sp(4,Z).