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In this paper we describe explicit generating functions for a large class of Hurwitz-Hodge integrals. These are integrals of tautological classes on moduli spaces of admissible covers, a (stackily) smooth compactification of the Hurwitz…

Algebraic Geometry · Mathematics 2007-05-23 Renzo Cavalieri

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…

Algebraic Geometry · Mathematics 2007-05-23 Ian Goulden , David Jackson , Ravi Vakil

In this paper we find an explicit formula for the number of topologically different ramified coverings $C\to\CP^1$ (C is a compact Riemann surface of genus g) with only one complicated branching point in terms of Hodge integrals over the…

Algebraic Geometry · Mathematics 2009-10-31 Torsten Ekedahl , Sergei Lando , Michael Shapiro , Alek Vainshtein

This article is an extended version of preprint math.AG/9902104. We find an explicit formula for the number of topologically different ramified coverings of a sphere by a genus g surface with only one complicated branching point in terms of…

Algebraic Geometry · Mathematics 2009-10-31 T. Ekedahl , S. Lando , M. Shapiro , A. Vainshtein

Double Hurwitz numbers enumerating weighted $n$-sheeted branched coverings of the Riemann sphere or, equivalently, weighted paths in the Cayley graph of $S_n$ generated by transpositions are determined by an associated weight generating…

Mathematical Physics · Physics 2018-06-26 Mathieu Guay-Paquet , J. Harnad

This manuscript studies a special case of the Hurwitz enumeration problem: for branched covers from genus g compact Riemann surface to the Riemann sphere, with three branch points, and require the branching data at one of the branch points…

Combinatorics · Mathematics 2026-05-26 Yi Song

We explain how Gaussian integrals over ensemble of complex matrices with source matrices generate Hurwitz numbers of the most general type, namely, Hurwitz numbers with arbitrary orientable or non-orientable base surface and arbitrary…

Mathematical Physics · Physics 2020-03-10 Sergei M. Natanzon , Aleksandr Yu. Orlov

Analogue of classical Hurwitz numbers is defined in the work for regular coverings of surfaces with marked points by seamed surfaces. Class of surfaces includes surfaces of any genus and orientability, with or without boundaries; coverings…

Geometric Topology · Mathematics 2007-09-25 A. V. Alexeevski , S. M. Natanzon

In this paper, we aim to provide an accessible survey to various formulae for calculating single Hurwitz numbers. Single Hurwitz numbers count certain classes of meromorphic functions on complex algebraic curves and have a rich geometric…

Algebraic Geometry · Mathematics 2020-02-25 Jared Ongaro

Hurwitz numbers enumerate ramified coverings of the Riemann sphere with fixed ramification data. Certain kinds of ramification data are of particular interest, such as double Hurwitz numbers, which count covers with fixed arbitrary…

Combinatorics · Mathematics 2018-10-09 Marvin Anas Hahn

We shall consider the product of complex random matrices from the independent complex Ginibre ensembles. The product includes complex matrices $Z_i, Z_i^\dagger, \, i = 1, \ldots, n$ and $2n$ sources (complex matrices $C_i$ and $C_i^*$).…

Mathematical Physics · Physics 2018-09-14 A. Yu. Orlov

In 1891, Hurwitz introduced the enumeration of genus $g$, degree $d$, branched covers of the Riemann sphere with simple ramification over prescribed points and no branching elsewhere. He showed that for fixed degree $d$, the enumeration…

Combinatorics · Mathematics 2024-09-11 Norman Do , Jian He , Heath Robertson

Simple Hurwitz numbers enumerate branched morphisms between Riemann surfaces with fixed ramification data. In recent years, several variants of this notion for genus $0$ base curves have appeared in the literature. Among them are so-called…

Algebraic Geometry · Mathematics 2022-11-02 Marvin Anas Hahn , Jan-Willem M. van Ittersum , Felix Leid

Hurwitz numbers count branched covers of the Riemann sphere with specified ramification data, or equivalently, transitive permutation factorizations in the symmetric group with specified cycle types. Monotone Hurwitz numbers count a…

Combinatorics · Mathematics 2019-08-15 I. P. Goulden , Mathieu Guay-Paquet , Jonathan Novak

Edge-contraction operations form an effective tool in various graph enumeration problems, such as counting Grothendieck's dessins d'enfants and simple and double Hurwitz numbers. These counting problems can be solved by a mechanism known as…

Algebraic Geometry · Mathematics 2019-08-16 Olivia Dumitrescu , Motohico Mulase

Double Hurwitz numbers count branched covers of the projective line with fixed branch points, with simple branching required over all but two points 0 and infinity, and the branching over 0 and infinity specified by partitions of the degree…

Algebraic Geometry · Mathematics 2007-05-23 Ian Goulden , David Jackson , Ravi Vakil

Let G be the group A_4 or Z_2xZ_2. We compute the integral of \lambda_g on the Hurwitz locus H_G\subset M_g of curves admitting a degree 4 cover of P^1 having monodromy group G. We compute the generating functions for these integrals and…

Algebraic Geometry · Mathematics 2007-09-03 Jim Bryan , Amin Gholampour

We are building a theory of simple Hurwitz numbers for the reflection groups B and D parallel to the classical theory for the symmetric group. We also study analogs of the cut-and-join operators. An algebraic description of Hurwitz numbers…

Combinatorics · Mathematics 2023-03-20 Raphaël Fesler

We are motivated by cone spherical metrics on compact Riemann surfaces of positive genus to solve a special case of the Hurwitz problem. Precisely speaking, letting $d,\,g$ and $\ell$ be three positive integers and $\Lambda$ be the…

Group Theory · Mathematics 2024-02-07 Jijian Song , Bin Xu , Yu Ye

Hurwitz numbers count ramified covers of a Riemann surface with prescribed monodromy. As such, they are purely combinatorial objects. Tautological classes, on the other hand, are distinguished classes in the intersection ring of the moduli…

Algebraic Geometry · Mathematics 2007-05-23 Aaron Bertram , Renzo Cavalieri , Gueorgui Todorov
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