Effective generic freeness and applications to local cohomology

Abstract

Let $A$ be a Noetherian domain and $R$ be a finitely generated $A$-algebra. We study several features regarding the generic freeness over $A$ of an $R$-module. For an ideal $I\subset R$, we show that the local cohomology modules ${\mathrm{H}}_I^i(R)$ are generically free over $A$ under certain settings where $R$ is a smooth $A$-algebra. By utilizing the theory of Gröbner bases over arbitrary Noetherian rings, we provide an effective method to make explicit the generic freeness over $A$ of a finitely generated $R$-module.

to appear in Journal of the London Mathematical Society