  Let A and A! be dual Koszul algebras. By Positselski a filtered algebra U
with gr U = A is Koszul dual to differential graded algebra (A!,d). We relate
the module categories of this dual pair by a tensor-Hom adjunction. This
descends to give an equivalence of suitable quotient categories and generalizes
work of Beilinson, Ginzburg and Soergel.
