V-filtrations and minimal exponents for locally complete intersection singularities

Fuente: arXiv
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Main Authors: Chen, Qianyu, Dirks, Bradley, Mustaţă, Mircea, Olano, Sebastián
Format: Preprint
Published: 2022
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author Chen, Qianyu
Dirks, Bradley
Mustaţă, Mircea
Olano, Sebastián
author_facet Chen, Qianyu
Dirks, Bradley
Mustaţă, Mircea
Olano, Sebastián
contents We define and study a notion of minimal exponent for a locally complete intersection subscheme $Z$ of a smooth complex algebraic variety $X$, extending the invariant defined by Saito in the case of hypersurfaces. Our definition is in terms of the Kashiwara-Malgrange $V$-filtration associated to $Z$. We show that the minimal exponent describes how far the Hodge filtration and order filtration agree on the local cohomology $H^r_Z({\mathcal O}_X)$, where $r$ is the codimension of $Z$ in $X$. We also study its relation to the Bernstein-Sato polynomial of $Z$. Our main result describes the minimal exponent of a higher codimension subscheme in terms of the invariant associated to a suitable hypersurface; this allows proving the main properties of this invariant by reduction to the codimension $1$ case. A key ingredient for our main result is a description of the Kashiwara-Malgrange $V$-filtration associated to any ideal $(f_1,\ldots,f_r)$ in terms of the microlocal $V$-filtration associated to the hypersurface defined by $\sum_{i=1}^rf_iy_i$.
format Preprint
id arxiv_https___arxiv_org_abs_2208_03277
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle V-filtrations and minimal exponents for locally complete intersection singularities
Chen, Qianyu
Dirks, Bradley
Mustaţă, Mircea
Olano, Sebastián
Algebraic Geometry
14F10, 14B05, 14J17
We define and study a notion of minimal exponent for a locally complete intersection subscheme $Z$ of a smooth complex algebraic variety $X$, extending the invariant defined by Saito in the case of hypersurfaces. Our definition is in terms of the Kashiwara-Malgrange $V$-filtration associated to $Z$. We show that the minimal exponent describes how far the Hodge filtration and order filtration agree on the local cohomology $H^r_Z({\mathcal O}_X)$, where $r$ is the codimension of $Z$ in $X$. We also study its relation to the Bernstein-Sato polynomial of $Z$. Our main result describes the minimal exponent of a higher codimension subscheme in terms of the invariant associated to a suitable hypersurface; this allows proving the main properties of this invariant by reduction to the codimension $1$ case. A key ingredient for our main result is a description of the Kashiwara-Malgrange $V$-filtration associated to any ideal $(f_1,\ldots,f_r)$ in terms of the microlocal $V$-filtration associated to the hypersurface defined by $\sum_{i=1}^rf_iy_i$.
title V-filtrations and minimal exponents for locally complete intersection singularities
topic Algebraic Geometry
14F10, 14B05, 14J17
url https://arxiv.org/abs/2208.03277