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arXiv math/9910004math.AGmath.CO
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点的Gromov-Witten势、Hurwitz数和Hodge积分

The Gromov-Witten potential of a point, Hurwitz numbers, and Hodge integrals

Ian Goulden, David Jackson, Ravi Vakil

摘要:

赫维茨数(英语:Hurwitz numbers),计算投影线的某些覆盖(或等价地,置换到转置的因式分解),已经被广泛研究了一个多世纪。曲线模空间上点的Gromov-Witten势F是曲线的Hodge积分的生成级数,一直是Gromov-Witten理论研究的中心对象。我们定义了一个稍微丰富的Gromov-Witten势G(包括包含一个“类”的积分),并证明了在变量的非平凡变量变换后,G=H在正亏格中,其中H是Hurwitz数的生成级数.本文证明了Goulden和Jackson关于高亏格Hurwitz数的一个猜想,它是Itzykson和Zuber关于亏格扩张的一个类似猜想.作为结果,我们有新的组合约束F,和一个更直接的证明的anonymous的Itzykson和Zuber。我们可以为Hurwitz数生成递归和显式公式;给出的算法应该证明“所有”这样的递归。此外,有更多的递归比以前怀疑从几何(事实上,他们应该存在于所有的属);作为例子,我们提出了令人惊讶的简单的新递归的属3是几何神秘的。正如我们期望本文也是组合学家的兴趣,我们试图使它尽可能独立,包括审查一些结果和定义众所周知的代数和辛几何,和数学物理。

英文摘要:

Hurwitz numbers, which count certain covers of the projective line (or, equivalently, factorizations of permuations into transpositions), have been extensively studied for over a century. The Gromov-Witten potential F of a point, the generating series for Hodge integrals on the moduli space of curves, has been a central object of study in Gromov-Witten theory. We define a slightly enriched Gromov-Witten potential G (including integrals involving one "lambda-class"), and show that after a non-trivial change of variables, G=H in positive genus, where H is a generating series for Hurwitz numbers. We prove a conjecture of Goulden and Jackson on higher genus Hurwitz numbers, which turns out to be an analogue of a genus expansion ansatz of Itzykson and Zuber. As consequences, we have new combinatorial constraints on F, and a much more direct proof of the ansatz of Itzykson and Zuber. We can produce recursions and explicit formulas for Hurwitz numbers; the algorithm presented should prove "all" such recursions. Furthermore, there are many more recursions than previously suspected from geometry (and indeed they should exist in all genera); as examples we present surprisingly simple new recursions in genus up to 3 that are geometrically mysterious. As we expect this paper also to be of interest to combinatorialists, we have tried to make it as self-contained as possible, including reviewing some results and definitions well known in algebraic and symplectic geometry, and mathematical physics.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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