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TEST IDEALS IN RINGS WITH FINITELY GENERATED ANTI-CANONICAL ALGEBRAS

Published online by Cambridge University Press:  13 January 2016

Alberto Chiecchio
Affiliation:
TASIS, Dorado, Puerto Rico (alberto.chiecchio@gmail.com)
Florian Enescu
Affiliation:
Department of Mathematics and Statistics, Georgia State University, Atlanta GA 30303, USA (fenescu@gsu.edu)
Lance Edward Miller
Affiliation:
Department of Mathematical Sciences, University of Arkansas, Fayetteville, AR 72701, USA (lem016@uark.edu)
Karl Schwede
Affiliation:
Department of Mathematics, University of Utah, 155 S 1400 E Room 233, Salt Lake City, UT, 84112, USA (schwede@math.utah.edu)

Abstract

Many results are known about test ideals and $F$-singularities for $\mathbb{Q}$-Gorenstein rings. In this paper, we generalize many of these results to the case when the symbolic Rees algebra ${\mathcal{O}}_{X}\oplus {\mathcal{O}}_{X}(-K_{X})\oplus {\mathcal{O}}_{X}(-2K_{X})\oplus \cdots \,$ is finitely generated (or more generally, in the log setting for $-K_{X}-\unicode[STIX]{x1D6E5}$). In particular, we show that the $F$-jumping numbers of $\unicode[STIX]{x1D70F}(X,\mathfrak{a}^{t})$ are discrete and rational. We show that test ideals $\unicode[STIX]{x1D70F}(X)$ can be described by alterations as in Blickle–Schwede–Tucker (and hence show that splinters are strongly $F$-regular in this setting – recovering a result of Singh). We demonstrate that multiplier ideals reduce to test ideals under reduction modulo $p$ when the symbolic Rees algebra is finitely generated. We prove that Hartshorne–Speiser–Lyubeznik–Gabber-type stabilization still holds. We also show that test ideals satisfy global generation properties in this setting.

Type
Research Article
Copyright
© Cambridge University Press 2016 

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