Koszul duality for finite-dimensional absolutely Koszul algebras

Abstract

Let \(\Lambda\) be a finite-dimensional Koszul algebra. Using a description of the linear part of minimal projective resolutions in terms of Koszul duality, we prove that \(\Lambda\) is absolutely Koszul if and only if its Koszul dual \(\Lambda^{!}\) is graded left co-coherent. As a consequence, every finite-dimensional graded module over a finite-dimensional absolutely Koszul algebra has a rational Poincar\'e series.We further show that an absolutely Koszul algebra of finite global linearity defect has finite graded finitistic dimension. Finally, we refine Koszul duality for finite-dimensional absolutely Koszul algebras. As a further application, we answer a question of Green et al.~\cite{12} by means of the Koszul dual algebra.