Tjurina spectrum and graded symmetry of missing spectral numbers

Fuente: arXiv
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Auteurs principaux: Jung, Seung-Jo, Kim, In-Kyun, Saito, Morihiko, Yoon, Youngho
Format: Preprint
Publié: 2024
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author Jung, Seung-Jo
Kim, In-Kyun
Saito, Morihiko
Yoon, Youngho
author_facet Jung, Seung-Jo
Kim, In-Kyun
Saito, Morihiko
Yoon, Youngho
contents For a hypersurface isolated singularity defined by a convergent power series $f$, the Steenbrink spectrum can be defined as the Poincaré polynomial of the graded quotients of the $V$-filtration on the Jacobian ring of $f$. The Tjurina subspectrum is defined by replacing the Jacobian ring with its quotient by the image of the multiplication by $f$. We prove that their difference (consisting of missing spectral numbers) has a canonical graded symmetry. This follows from the self-duality of the Jacobian ring, which is compatible with the action of $f$ as well as the $V$-filtration. It implies for instance that the number of missing spectral numbers which are smaller than $(n{+}1)/2$ (with $n$ the number of variables) is bounded by $[(μ{-}τ)/2]$. We can moreover improve the estimate of Briançon-Skoda exponent in the semisimple monodromy case.
format Preprint
id arxiv_https___arxiv_org_abs_2411_17601
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tjurina spectrum and graded symmetry of missing spectral numbers
Jung, Seung-Jo
Kim, In-Kyun
Saito, Morihiko
Yoon, Youngho
Algebraic Geometry
For a hypersurface isolated singularity defined by a convergent power series $f$, the Steenbrink spectrum can be defined as the Poincaré polynomial of the graded quotients of the $V$-filtration on the Jacobian ring of $f$. The Tjurina subspectrum is defined by replacing the Jacobian ring with its quotient by the image of the multiplication by $f$. We prove that their difference (consisting of missing spectral numbers) has a canonical graded symmetry. This follows from the self-duality of the Jacobian ring, which is compatible with the action of $f$ as well as the $V$-filtration. It implies for instance that the number of missing spectral numbers which are smaller than $(n{+}1)/2$ (with $n$ the number of variables) is bounded by $[(μ{-}τ)/2]$. We can moreover improve the estimate of Briançon-Skoda exponent in the semisimple monodromy case.
title Tjurina spectrum and graded symmetry of missing spectral numbers
topic Algebraic Geometry
url https://arxiv.org/abs/2411.17601