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We prove that every closed orientable surface S of negative Euler characteristic admits a pair of finite-degree covers which are length isospectral over S but generically not simple length isospectral over S. To do this, we first…

Geometric Topology · Mathematics 2023-07-19 Tarik Aougab , Max Lahn , Marissa Loving , Nicholas Miller

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

In classical differential geometry, a central question has been whether abstract surfaces with given geometric features can be realized as surfaces in Euclidean space. Inspired by the rich theory of embedded triply periodic minimal…

Differential Geometry · Mathematics 2018-09-18 Dami Lee

We show that every open Riemann surface can be obtained by glueing together a countable collection of equilateral triangles, in such a way that every vertex belongs to finitely many triangles. Equivalently, it is a _Belyi surface_: There…

Complex Variables · Mathematics 2025-09-19 Christopher J. Bishop , Lasse Rempe

We compute the number of (weak) equivalence classes of branched covers from a surface of genus g to the sphere, with 3 branching points, degree 2k, and local degrees over the branching points of the form (2,...,2), (2h+1,1,2,...,2),…

Geometric Topology · Mathematics 2018-09-06 Carlo Petronio

With each holomorphic map $f: R \rightarrow \mathbb C\mathbb P^1$, where $R$ is a compact Riemann surface, one can associate a combinatorial datum consisting of the genus $g$ of $R$, the degree $n$ of $f$, the number $q$ of branching points…

Geometric Topology · Mathematics 2025-05-08 Fedor Pakovich

Let X be a closed surface of genus two embedded in the 3-sphere. Then X inherits a metric and an orientation, which give an almost complex structure, which automatically integrates to a genuine complex structure, making X a Riemann surface.…

Complex Variables · Mathematics 2016-07-22 Neil Strickland

For compact Riemann surfaces, the collar theorem and Bers' partition theorem are major tools for working with simple closed geodesics. The main goal of this paper is to prove similar theorems for hyperbolic cone-surfaces. Hyperbolic…

Differential Geometry · Mathematics 2007-08-23 Emily B. Dryden , Hugo Parlier

We prove that a resolution of singularities of any finite covering of the projective plane branched along a Hurwitz curve $\bar H$ and, maybe, along a line "at infinity" can be embedded as a symplectic submanifold into some projective…

Symplectic Geometry · Mathematics 2015-06-26 G. -M. Greuel , Vik. S. Kulikov

We study branched covering spaces in several contexts, proving that under suitable circumstances the cover satisfies the same upper curvature bounds as the base space. The first context is of a branched cover of an arbitrary metric space…

Differential Geometry · Mathematics 2007-05-23 Daniel Allcock

With the help of hyper-ideal circle pattern theory, we have developed a discrete version of the classical uniformization theorems for surfaces represented as finite branched covers over the Riemann sphere as well as compact polyhedral…

Metric Geometry · Mathematics 2017-08-25 Alexander Bobenko , Nikolay Dimitrov , Stefan Sechelmann

We study "pure-cycle" Hurwitz spaces, parametrizing covers of the projective line having only one ramified point over each branch point. We start with the case of genus-0 covers, using a combination of limit linear series theory and group…

Algebraic Geometry · Mathematics 2007-05-23 Fu Liu , Brian Osserman

For an $n$-fold geometrically cyclic branched covering $Y$ of a smooth, projective scheme $X$ branched at a smooth closed subscheme $Z\subset X$ with $n \in k^\times$, we compute the quadratic Euler characteristic of $Y$ in terms of certain…

Algebraic Geometry · Mathematics 2026-05-14 Louisa F. Bröring

We give an alternative proof of the Hurwitz existence problem for branched covers of $\mathbb{P}^1$ in the case where the number of ramification points equals the number of branch points, that is, where all the ramification profiles are of…

Algebraic Geometry · Mathematics 2026-05-06 Ciro Ciliberto , Andreas Leopold Knutsen , Sara Torelli

Classes of branched surfaces extend the classes of surfaces or 2-dimensional manifolds satisfying suitable properties and defined in various manners. Reeb spaces of smooth maps of suitable classes into surfaces whose codimensions are…

General Topology · Mathematics 2022-08-16 Naoki Kitazawa

A degree $d$ genus $g$ cover of the complex projective line by a smooth curve $C$ yields a vector bundle on the projective line by pushforward of the structure sheaf. Which bundles are possible? Equivalently, which…

Algebraic Geometry · Mathematics 2026-05-29 Ravi Vakil , Sameera Vemulapalli

Pulling back complex structures along a branched covering induces a holomorphic isometric embedding of Teichm\"uller spaces. We show that for dimension at least $2$, all isometric embeddings arise from branched coverings. This generalizes a…

Geometric Topology · Mathematics 2023-05-09 Frederik Benirschke , Carlos A. Serván

A meromorphic quadratic differential with poles of order two, on a compact Riemann surface, induces a measured foliation on the surface, with a spiralling structure at any pole that is determined by the complex residue of the differential…

Geometric Topology · Mathematics 2016-07-26 Subhojoy Gupta , Michael Wolf

This article is devoted to examples of (orbifold) K\"ahler groups from the perspective of the so-called Shafarevich conjecture on holomorphic convexity. It aims at pointing out that every quasi-projective complex manifold with an…

Algebraic Geometry · Mathematics 2016-11-29 Philippe Eyssidieux

We prove that, under mild restrictions, the space of codimension-one foliations of degree one on a smooth projective complete intersection has two irreducible components of logarithmic type. We also prove that the same conclusion holds for…

Algebraic Geometry · Mathematics 2025-12-03 Mateus Figueira , Crislaine Kuster , Ruben Lizarbe , Alan Muniz