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arXiv · 1507.05459

F-thresholds of graded rings

Alessandro De Stefani·Luis Núñez-Betancourt
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Abstract

The a-invariant, the F-pure threshold, and the diagonal F-threshold are three important invariants of a graded K-algebra. Hirose, Watanabe, and Yoshida have conjectured relations among these invariants for strongly F-regular rings. In this article, we prove that these relations hold only assuming that the algebra is F-pure. In addition, we present an interpretation of the a-invariant for F-pure Gorenstein graded K-algebras in terms of regular sequences that preserve F-purity. This result is in the spirit of Bertini theorems for projective varieties. Moreover, we show connections with projective dimension, Castelnuovo-Mumford regularity, and Serre's condition $S_k$. We also present analogous results and questions in characteristic zero.

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Alessandro De Stefani, Luis Núñez-Betancourt. 2015-07-20. F-thresholds of graded rings. https://arxiv.org/abs/1507.05459

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