Independence of tautological classes and cohomological stability for strata of differentials

Fuente: arXiv
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Hauptverfasser: Chen, Dawei, Larson, Hannah
Format: Preprint
Veröffentlicht: 2026
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author Chen, Dawei
Larson, Hannah
author_facet Chen, Dawei
Larson, Hannah
contents The tautological rings of strata of differentials are known to be generated by divisor classes. In this paper, we give lower bounds on the degrees of relations among them, depending on the genus $g$ and the number of simple zeros. For strata with more than $4g/3$ simple zeros, our results show that there are no relations in degrees less than $\lfloor g/3 \rfloor + 1$. Moreover, we conjecture that, outside of a few exceptions, there is always a non-trivial relation in degree $\lfloor g/3 \rfloor + 1$, and prove the conjecture for all strata of holomorphic abelian differentials with $g \leq 30$. We also prove that the cohomology rings of strata of holomorphic differentials with sufficiently many simple zeros stabilize to the free algebra on the tautological divisor class. Finally, we show that for a large class of holomorphic abelian strata, containing hyperelliptic differentials, the tautological ring is non-trivial for sufficiently large $g$.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23850
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Independence of tautological classes and cohomological stability for strata of differentials
Chen, Dawei
Larson, Hannah
Algebraic Geometry
Geometric Topology
The tautological rings of strata of differentials are known to be generated by divisor classes. In this paper, we give lower bounds on the degrees of relations among them, depending on the genus $g$ and the number of simple zeros. For strata with more than $4g/3$ simple zeros, our results show that there are no relations in degrees less than $\lfloor g/3 \rfloor + 1$. Moreover, we conjecture that, outside of a few exceptions, there is always a non-trivial relation in degree $\lfloor g/3 \rfloor + 1$, and prove the conjecture for all strata of holomorphic abelian differentials with $g \leq 30$. We also prove that the cohomology rings of strata of holomorphic differentials with sufficiently many simple zeros stabilize to the free algebra on the tautological divisor class. Finally, we show that for a large class of holomorphic abelian strata, containing hyperelliptic differentials, the tautological ring is non-trivial for sufficiently large $g$.
title Independence of tautological classes and cohomological stability for strata of differentials
topic Algebraic Geometry
Geometric Topology
url https://arxiv.org/abs/2603.23850