Title: Derivations of Group Algebras and Hochschild Cohomology
Abstract: This article is based on the author’s talk at the international conference dedicated to the memory of Professor B. Yu. Sternin (Moscow, November 6–9, 2018). The Hochschild homology and cohomology of a group algebra can be described via the homology and cohomology of the classifying space of the adjoint action groupoid of the group under a suitable assumption on the finiteness of supports of the cohomology groups. The difference between homology and cohomology leads to a correction to results in D. J. Benson’s book Representations and cohomology (vols. I–II, Cambridge Univ. Press, Cambridge, 1991).