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We present a review of the spin Hurwitz numbers, which count the ramified coverings with spin structures. They are related to peculiar $Q$ Schur functions, which are actually related to characters of the Sergeev group. This allows one to…

Mathematical Physics · Physics 2021-10-15 A. D. Mironov , A. Yu Morozov , S. M. Natanzon , A. Yu Orlov

Hurwitz spaces which parametrize branched covers of the line play a prominent role in inverse Galois theory. This paper surveys fifty years of works in this direction with emphasis on recent advances. Based on the Riemann-Hurwitz theory of…

Number Theory · Mathematics 2026-04-14 Pierre Dèbes

For a Fermat quasi-homogeneous polynomial, we study the associated weighted Fan-Jarvis-Ruan-Witten theory with narrow insertions. We prove a wall-crossing formula in all genera via localization on a master space, which is constructed by…

Algebraic Geometry · Mathematics 2019-04-25 Yang Zhou

We investigate the universal Jacobian of degree n line bundles over the Hurwitz stack of double covers of P^1 by a curve of genus g. Our main results are: the construction of a smooth, irreducible, universally closed (but not separated)…

Algebraic Geometry · Mathematics 2018-04-30 Daniel Erman , Melanie Matchett Wood

We are extending results from \cite{B-Hurwitz} by building a parallel theory of simple Hurwitz numbers for the reflection groups $G(m,1,n)$. We also study analogs of the cut-and-join operators. An algebraic description as well as a…

Combinatorics · Mathematics 2024-03-05 Raphaël Fesler , Denis Gorodkov , Maksim Karev

In this paper we set up the family Seiberg-Witten theory. It can be applied to the counting of nodal pseudo-holomorphic curves in a symplectic 4-manifold (especially a Kahler surface). A new feature in this theory is that the chamber…

Geometric Topology · Mathematics 2007-05-23 Tian-Jun Li , Ai-Ko Liu

We consider multi-matrix models that are generating functions for the numbers of branched covers of the complex projective line ramified over $n$ fixed points $z_i$, $i=1,\dots,n$, (generalized Grotendieck's dessins d'enfants) of fixed…

Mathematical Physics · Physics 2018-08-15 Jan Ambjørn , Leonid O. Chekhov

We consider the problem of defining and computing real analogs of polynomial Hurwitz numbers, in other words, the problem of counting properly normalized real polynomials with fixed ramification profiles over real branch points. We show…

Algebraic Geometry · Mathematics 2018-12-12 Ilia Itenberg , Dimitri Zvonkine

In general, Hurwitz numbers count branched covers of the Riemann sphere with prescribed ramification data, or equivalently, factorisations in the symmetric group with prescribed cycle structure data. In this paper, we initiate the study of…

Geometric Topology · Mathematics 2015-11-10 Norman Do , Maksim Karev

We determine the decomposition numbers for the Brauer and walled Brauer algebra in characteristic zero in terms of certain polynomials associated to cap and curl diagrams (recovering a result of Martin in the Brauer case). We consider a…

Representation Theory · Mathematics 2010-09-22 Anton Cox , Maud De Visscher

We present a polynomial partitioning theorem for finite sets of points in the real locus of an irreducible complex algebraic variety of codimension at most two. This result generalizes the polynomial partitioning theorem on the Euclidean…

Algebraic Geometry · Mathematics 2015-09-22 Saugata Basu , Martin Sombra

Monotone Hurwitz numbers were introduced by the authors as a combinatorially natural desymmetrization of the Hurwitz numbers studied in enumerative algebraic geometry. Over the course of several papers, we developed the structural theory of…

Combinatorics · Mathematics 2016-06-02 I. P. Goulden , Mathieu Guay-Paquet , Jonathan Novak

Recently a new family of enumerative invariants called leaky Hurwitz numbers was introduced by Cavalieri-Markwig-Ranganathan in the context of logarithmic intersection theory. They admit an interpretation via tropical covers where the…

Algebraic Geometry · Mathematics 2026-03-09 Marvin Anas Hahn , Reinier Kramer

In this short note, we propose a definition of complete Hurwitz schemes (and stacks) in mixed characteristic. We follow an idea of R. Pandharipande, and define the complete Hurwitz stack as a substack of stable maps of degree d of nodal…

Algebraic Geometry · Mathematics 2007-05-23 Dan Abramovich , Frans Oort

An arithmetical structure on a graph is given by a labeling of the vertices which satisfies certain divisibility properties. In this note, we look at several families of graphs and attempt to give counts on the number of arithmetical…

Combinatorics · Mathematics 2019-03-05 Darren Glass , Joshua Wagner

Moduli spaces of algebraic curves and closely related to them Hurwitz spaces, that is, spaces of meromorphic functions on the curves, arise naturally in numerous problems of algebraic geometry and mathematical physics, especially in…

Algebraic Geometry · Mathematics 2015-06-26 M. E. Kazaryan , S. K. Lando

Modular curves $X_{1}(N)$ parametrize elliptic curves with a point of order $N$. They can be identified with connected components of projectivized strata $\mathbb{P}\mathcal{H}(a,-a)$ of meromorphic differentials. As strata of meromorphic…

Algebraic Geometry · Mathematics 2019-02-06 Guillaume Tahar

Hurwitz numbers enumerate branched morphisms between Riemann surfaces. For a fixed elliptic target, Hurwitz numbers are intimately related to mirror symmetry following work of Dijkgraaf. In recent work of Chapuy and Dolega a new variant of…

Combinatorics · Mathematics 2024-10-28 Marvin Anas Hahn , Hannah Markwig

For a finite group $G$ and a conjugation-invariant subset $Q\subseteq G$, we consider the Hurwitz space $\mathrm{Hur}_n(Q)$ parametrising branched covers of the plane with $n$ branch points, monodromies in $G$ and local monodromies in $Q$.…

Algebraic Topology · Mathematics 2024-09-27 Andrea Bianchi , Jeremy Miller

This manuscript recounts some of the author's contributions to algebraic and enumerative combinatorics. We have focused on two types of generalizations of bipartite maps, which are bipartite graphs embedded on surfaces. Maps are known to…

Combinatorics · Mathematics 2023-02-14 Valentin Bonzom