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arXiv · 1009.1271

Powers of ideals and the cohomology of stalks and fibers of morphisms

Marc Chardin
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Abstract

We first provide here a very short proof of a refinement of a theorem of Kodiyalam and Cutkosky, Herzog and Trung on the regularity of powers of ideals. This result implies a conjecture of H\`a and generalizes a result of Eisenbud and Harris concerning the case of ideals primary for the graded maximal ideal in a standard graded algebra over a field. It also implies a new result on the regularities of powers of ideal sheaves. We then compare the cohomology of the stalks and the cohomology of the fibers of a projective morphism to the effect of comparing the maximum over fibers and over stalks of the Castelnuovo-Mumford regularities of a family of projective schemes.

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Marc Chardin. 2010-09-07. Powers of ideals and the cohomology of stalks and fibers of morphisms. https://arxiv.org/abs/1009.1271

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