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arXiv · 1208.2187

The lex-plus-power inequality for local cohomology modules

Giulio Caviglia·Enrico Sbarra
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Abstract

We prove an inequality between Hilbert functions of local cohomology modules supported in the homogeneous maximal ideal of standard graded algebras over a field, within the framework of embeddings of posets of Hilbert functions. As a main application, we prove an analogue for local cohomology of Evans' Lex-Plus-Power Conjecture for Betti numbers. This results implies some cases of the classical Lex-Plus-Power Conjecture, namely an inequality between extremal Betti numbers. In particular, for the classes of ideals for which the Eisenbud-Green-Harris Conjecture is currently known, the projective dimension and the Castelnuovo-Mumford regularity of a graded ideal do not decrease by passing to the corresponding Lex-Plus-Power ideal.

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Giulio Caviglia, Enrico Sbarra. 2012-08-10. The lex-plus-power inequality for local cohomology modules. https://arxiv.org/abs/1208.2187

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