Integral Chow rings of modular compactifications of $\mathcal{M}_{1,n\leq 6}$

Fuente: arXiv
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Auteurs principaux: Battistella, Luca, Di Lorenzo, Andrea
Format: Preprint
Publié: 2025
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author Battistella, Luca
Di Lorenzo, Andrea
author_facet Battistella, Luca
Di Lorenzo, Andrea
contents For $n\leq 6$, we compute the integral Chow ring of every modular compactification of $\mathcal{M}_{1,n}$ parametrising only Gorenstein curves with smooth, distinct markings. These include the Deligne--Mumford, Schubert, and Smyth compactifications, and many more. They can all be excised from the stack of log-canonically polarised Gorenstein curves. The Chow ring of the latter admits a simple, combinatorial description, which we compute by patching along a natural stratification by core level. We further deduce that all these modular compactifications satisfy the Chow-Künneth generation property, that the cycle class map is an isomorphism, and for $n=4$ we study whether the Getzler's relation hold integrally.
format Preprint
id arxiv_https___arxiv_org_abs_2505_04587
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Integral Chow rings of modular compactifications of $\mathcal{M}_{1,n\leq 6}$
Battistella, Luca
Di Lorenzo, Andrea
Algebraic Geometry
14C15, 14H10
For $n\leq 6$, we compute the integral Chow ring of every modular compactification of $\mathcal{M}_{1,n}$ parametrising only Gorenstein curves with smooth, distinct markings. These include the Deligne--Mumford, Schubert, and Smyth compactifications, and many more. They can all be excised from the stack of log-canonically polarised Gorenstein curves. The Chow ring of the latter admits a simple, combinatorial description, which we compute by patching along a natural stratification by core level. We further deduce that all these modular compactifications satisfy the Chow-Künneth generation property, that the cycle class map is an isomorphism, and for $n=4$ we study whether the Getzler's relation hold integrally.
title Integral Chow rings of modular compactifications of $\mathcal{M}_{1,n\leq 6}$
topic Algebraic Geometry
14C15, 14H10
url https://arxiv.org/abs/2505.04587