Resolutions over Koszul algebras

Abstract

In this paper we show that if $\Lambda=\amalg_{i\geq 0}\Lambda_i$ is a Koszul algebra with $\Lambda_0$ isomorphic to a product of copies of a field, then the minimal projective resolution of $\Lambda_0$ as a right $\Lambda$-module provides all the information necessary to construct both a minimal projective resolution of $\Lambda_0$ as a left $\Lambda$-module and a minimal projective resolution of $\Lambda$ as a right module over the enveloping algebra of $\Lambda$. The main tool for this is showing that there is a comultiplicative structure on a minimal projective resolution of $\Lambda_0$ as a right $\Lambda$-module.