2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/60797Let $g$ be a reductive Lie algebra over a field of characteristic zero. Suppose $g$ acts on a complex of vector spaces $M$ by $i_λ$ and $L_λ$, which satisfy the identities as contraction and Lie derivative do for smooth differential forms. Out of this data one defines cohomology of the invariants and equivariant cohomology of $M$. We establish Koszul duality between each other.11 pages, LaTeX, final version: to appear in Duke Math. JAlgebraic Geometrytext