Selfextensions of modules over group algebras

Bernhard Böhmler, Karin Erdmann, Viktória Klász +1

Let $KG$ be a group algebra with $G$ a finite group and $K$ a field and $M$ an indecomposable $KG$-module. We pose the question, whether $Ex{t}_{KG}^1(M,M)\ne 0$ implies that $Ext_…