The tautological ring of $\overline{\mathcal{M}}_{g,n}$ is rarely Gorenstein

Fuente: arXiv
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Main Author: Canning, Samir
Format: Preprint
Published: 2024
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_version_ 1866909845185101824
author Canning, Samir
author_facet Canning, Samir
contents We prove that the tautological rings $\mathsf{R}^*(\overline{\mathcal{M}}_{g,n})$ and $\mathsf{RH}^*(\overline{\mathcal{M}}_{g,n})$ are not Gorenstein when $g\geq 2$ and $2g+n\geq 24$, extending results of Petersen and Tommasi in genus $2$. The proof uses the intersection of tautological classes with non-tautological bielliptic cycles. We conjecture the converse: the tautological rings should be Gorenstein when $g=0,1$ or $g\geq 2$ and $2g+n<24$. The conjecture is known for $g=0,1$ by work of Keel and Petersen, and we prove several new cases of this conjecture for $\mathsf{RH}^*(\overline{\mathcal{M}}_{g,n})$ when $g\geq 2$.
format Preprint
id arxiv_https___arxiv_org_abs_2406_10516
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The tautological ring of $\overline{\mathcal{M}}_{g,n}$ is rarely Gorenstein
Canning, Samir
Algebraic Geometry
14C15, 14C17
We prove that the tautological rings $\mathsf{R}^*(\overline{\mathcal{M}}_{g,n})$ and $\mathsf{RH}^*(\overline{\mathcal{M}}_{g,n})$ are not Gorenstein when $g\geq 2$ and $2g+n\geq 24$, extending results of Petersen and Tommasi in genus $2$. The proof uses the intersection of tautological classes with non-tautological bielliptic cycles. We conjecture the converse: the tautological rings should be Gorenstein when $g=0,1$ or $g\geq 2$ and $2g+n<24$. The conjecture is known for $g=0,1$ by work of Keel and Petersen, and we prove several new cases of this conjecture for $\mathsf{RH}^*(\overline{\mathcal{M}}_{g,n})$ when $g\geq 2$.
title The tautological ring of $\overline{\mathcal{M}}_{g,n}$ is rarely Gorenstein
topic Algebraic Geometry
14C15, 14C17
url https://arxiv.org/abs/2406.10516