Koszul Duality for Coherent Sheaves

We establish a bounded derived Koszul duality for infinite-dimensional Koszul algebras, and we obtain the corresponding singular Koszul duality. We then apply this framework to two classes of Koszul algebras, namely quadratic monomial algebras and absolutely Koszul algebras satisfying an additional homological condition. For these classes, the general duality specializes to particularly well-behaved forms. As an application to algebraic geometry, let $\Lambda$ be a commutative noetherian Koszul algebra generated in degree $1$, and let $X=\operatorname{Proj}(\Lambda)$. We obtain a Koszul-dual description of the bounded derived category $\mathsf{D}^{b}\!\bigl(\operatorname{coh}(X)\bigr)$. This gives a BGG-type correspondence for projective schemes defined by commutative noetherian Koszul algebras.