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arXiv 2601.04430math.AG
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曲线模空间中最大变化区域

Maximal Variation in the Moduli of Curves

Xiamen University Malaysia(马来西亚厦门大学)

Mounir Nisse

AI总结:

本文研究了曲线模空间中最大变化区域的性质,揭示了非Gorenstein奇点对退化的影响,并建立了退化区域的分类方法。

摘要:

我们引入并研究了在曲线族和模空间中的最大变化区域,其定义通过正则级数上的多元有理微分的导数平衡来实现。这一概念精确捕捉了当canonical不同微分空间在退化时表现出预期维度的行为。我们证明了半连续性和开放性结果,表明最大变化在平坦族中是稳定的,识别了一个自然的行列式退化区域,其中最大变化失效,并证明这种失效完全由非Gorenstein奇点的存在所支配。特别是,所有光滑和节点曲线都满足最大变化,而每个非Gorenstein奇点都显式且加性地导致退化。我们计算了退化区域的预期余维数,描述了它们在模空间中的闭包和邻接关系,并解释了非Gorenstein缺陷如何在退化中导致额外的Hodge理论现象。这一框架提供了一种统一、内在且变形理论上有意义的退化分类方法。

英文摘要:

We introduce and study the maximal-variation locus in families and moduli spaces of projective curves, defined via conductor-level balancing of meromorphic differentials on the normalization. This notion captures precisely when the space of canonical differentials behaves with the expected dimension under degeneration. We prove semicontinuity and openness results showing that maximal variation is stable in flat families, identify a natural determinantal degeneracy locus where maximal variation fails, and establish that this failure is governed entirely by the presence of non-Gorenstein singularities. In particular, all smooth and nodal curves satisfy maximal variation, while every non-Gorenstein singularity contributes explicitly and additively to degeneracy. We compute the expected codimension of degeneracy loci, describe their closure and adjacency relations in moduli, and explain how non-Gorenstein defects give rise to additional Hodge-theoretic phenomena in degenerations. This framework provides a uniform, intrinsic, and deformation-theoretically meaningful classification of degeneracy in spaces of canonical differentials.

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