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In this paper we study topology of moduli spaces of tropical curves of genus $g$ with $n$ marked points. We view the moduli spaces as being imbedded in a larger space, which we call the {\it moduli space of metric graphs with $n$ marked…

Algebraic Topology · Mathematics 2008-09-26 Dmitry N. Kozlov

We suggest a general method of computation of the homology of certain smooth covers $\hat{\mathcal{M}}_{g,1}(\mathbb{C})$ of moduli spaces $\mathcal{M}_{g,1}\br{\mathbb{C}}$ of pointed curves of genus $g$. Namely, we consider moduli spaces…

Algebraic Geometry · Mathematics 2015-03-11 Petr Dunin-Barkowski , Alexander Popolitov , George Shabat , Alexei Sleptsov

By associating to a curve C of genus g=2k and a pencil of degree d=k+1 the so-called trace curve (resp. the reduced trace curve) we define a rational map from the Hurwitz space of admissible covers of genus g=2k and degree d=k+1 to a moduli…

Algebraic Geometry · Mathematics 2011-05-13 Gerard van der Geer , Alexis Kouvidakis

Given a smooth, projective curve $Y$, a point $y_0 \in Y$, a positive integer $n$, and a transitive subgroup $G$ of the symmetric group $S_{d}$ we study smooth, proper families, parameterized by algebraic varieties, of pointed degree $d$…

Algebraic Geometry · Mathematics 2025-10-21 Vassil Kanev

In this survey article we give an overview of how noncongruence modular curves can be viewed as Hurwitz moduli spaces of covers of elliptic curves at most branched above the origin. We describe some natural questions that arise, and…

Number Theory · Mathematics 2025-10-15 William Y. Chen

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 provide a direct correspondence between the $b$-Hurwitz numbers with $b=1$ from \cite{ChapuyDolega}, and twisted Hurwtiz numbers from \cite{TwistedHurwitz}. This provides a description of real coverings of the sphere with ramification on…

Algebraic Geometry · Mathematics 2024-03-12 Yurii Burman , Raphaël Fesler

We describe the hyperplane sections of the Severi variety of curves in $E \times \mathbb{P}^1$ in a similar fashion to Caporaso-Harris' seminal work. From this description we almost get a recursive formula for the Severi degrees (we get the…

Algebraic Geometry · Mathematics 2014-09-04 Gabriel Bujokas

Hurwitz numbers count ramified genus $g$, degree $d$ coverings of the projective line with with fixed branch locus and fixed ramification data. Double Hurwitz numbers count such covers, where we fix two special profiles over $0$ and…

Combinatorics · Mathematics 2018-07-11 Marvin Anas Hahn

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 continue our computation, using a combinatorial method based on Gronthendieck's dessins d'enfant, of the number of (weak) equivalence classes of surface branched covers matching certain specific branch data. In this note we concentrate…

Geometric Topology · Mathematics 2018-07-31 Carlo Petronio

Hurwitz numbers count genus g, degree d covers of the projective line with fixed branch locus. This equals the degree of a natural branch map defined on the Hurwitz space. In tropical geometry, algebraic curves are replaced by certain…

Algebraic Geometry · Mathematics 2010-07-19 Renzo Cavalieri , Paul Johnson , Hannah Markwig

We introduce and study a semigroup structure on the set of irreducible components of the Hurwitz space of marked coverings of a complex projective curve with given Galois group of the coverings and fixed ramification type. As application,…

Algebraic Geometry · Mathematics 2012-05-23 V. Kharlamov , Vik. Kulikov

We define the tropical moduli space of covers of a tropical line in the plane as weighted abstract polyhedral complex, and the tropical branch map recording the images of the simple ramifications. Our main result is the invariance of the…

Algebraic Geometry · Mathematics 2013-10-29 Arne Buchholz , Hannah Markwig

This is a survey paper dealing with moduli aspects of curves over finite fields. It discusses counting points of moduli spaces, relations with modular forms and stratifications on moduli spaces.

Algebraic Geometry · Mathematics 2022-10-27 Gerard van der Geer

In this work we study the additive orbifold cohomology of the moduli stack of smooth genus g curves. We show that this problem reduces to investigating the rational cohomology of moduli spaces of cyclic covers of curves where the genus of…

Algebraic Geometry · Mathematics 2013-12-20 Nicola Pagani , Orsola Tommasi

Curves of genus g which admit a map to CP1 with specified ramification profile mu over 0 and nu over infinity define a double ramification cycle DR_g(mu,nu) on the moduli space of curves. The study of the restrictions of these cycles to the…

Algebraic Geometry · Mathematics 2024-09-24 F. Janda , R. Pandharipande , A. Pixton , D. Zvonkine

We study genus $g$ coverings of full moduli dimension of degree $d=[\frac {g+3} 2]$. There is a homomorphism between the corresponding Hurwitz space $\H$ of such covers to the moduli space $\M_g$ of genus $g$ curves. In the case $g=3$,…

Algebraic Geometry · Mathematics 2012-09-05 T. Shaska , J. L. Thompson

A well-known and difficult problem in computational number theory and algebraic geometry is to write down equations for branched covers of algebraic curves with specified monodromy type. In this article, we present a technique for computing…

Algebraic Geometry · Mathematics 2014-07-07 Simon Rubinstein-Salzedo

Let $\mathcal H_g$ be the moduli space of genus $g$ hyperelliptic curves. In this note, we study the locus $\mathcal L$ in $\mathcal H_g$ of curves admitting a $G$-action of given ramification type $\sigma$ and inclusions between such loci.…

Algebraic Geometry · Mathematics 2013-02-19 T. Shaska