Integral Chow rings of modular compactifications of $\mathcal{M}_{1,n\leq 6}$
Algebraic Geometry
2026-04-08 v2
Abstract
For , we compute the integral Chow ring of every modular compactification of 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-K\"{u}nneth generation property, that the cycle class map is an isomorphism, and for we study whether the Getzler's relation hold integrally.
Cite
@article{arxiv.2505.04587,
title = {Integral Chow rings of modular compactifications of $\mathcal{M}_{1,n\leq 6}$},
author = {Luca Battistella and Andrea Di Lorenzo},
journal= {arXiv preprint arXiv:2505.04587},
year = {2026}
}
Comments
v2: final version, to appear on Crelle