The structure of blocks with a Klein four defect group

David A. Craven, Charles W. Eaton, Radha Kessar and Markus Linckelmann

Abstract. We prove Erdmann's conjecture [15] stating that every block
with a Klein four defect group has a simple module with trivial source,
and deduce from this that Puig's finiteness conjecture holds for 
source algebras of blocks with Klein four defect group. The proof uses
the classification of finite simple groups.