A little bit of extra functoriality for Ext and the computation of the Gerstenhaber bracket

Abstract

We show that the action of the Lie algebra HH1(A) of outer derivations of an associative algebra A on the Hochschild cohomology HH•(A) of A given by the Gerstenhaber bracket can be computed in terms of an arbitrary projective resolution of A as an A-bimodule, without having recourse to comparison maps between the resolution and the bar resolution.