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arXiv · 2307.07906

Multiplier ideals and klt singularities via (derived) splittings

Peter M. McDonald
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Abstract

Let $X$ be a normal, excellent, noetherian scheme over $\operatorname{Spec}\mathbb{Q}$ with a dualizing complex. In this note, we find an alternate characterization of the multiplier ideal of $X$, as defined by de Fernex-Hacon, by considering maps $π_*ω_Y\to\mathcal{O}_X$ where $π:Y\to X$ ranges over all regular alterations. As a corollary to this result, we give a derived splinter characterization of klt singularities, akin to the characterization of rational singularities given by Kovács and Bhatt. We also give an analogous description of the test ideal in characteristic $p>2$ as a corollary to a result of Epstein-Schwede.

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Peter M. McDonald. 2026-03-10. Multiplier ideals and klt singularities via (derived) splittings. https://doi.org/10.4310/mrl.251215012546

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