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The matching complex of a graph $G$ is a simplicial complex whose simplices are matchings in $G$. In the last few years the matching complexes of grid graphs have gained much attention among the topological combinatorists. In 2017, Braun…

Combinatorics · Mathematics 2025-11-27 Shuchita Goyal , Samir Shukla , Anurag Singh

We show there exists a closed graph manifold $N$ and infinitely many non-separable, horizontal surfaces $\{S_{n} \to N\}_{n \in \mathbb{N}}$ such that there does not exist a quasi-isometry $\pi_1(N) \to \pi_1(N)$ taking $\pi_1(S_{n})$ to…

Group Theory · Mathematics 2018-08-09 Hoang Thanh Nguyen

The Gordian graph and H(2)-Gordian graphs of knots are abstract graphs whose vertex sets represent isotopy classes of unoriented knots, and whose edge sets record whether pairs of knots are related by crossing changes or H(2)-moves,…

Geometric Topology · Mathematics 2021-11-24 Christopher Flippen , Allison H. Moore , Essak Seddiq

The pinched sphere is the pseudo-surface $\mathbb{S}^{\circ}_0$ obtained by identifying two distinct points of the sphere. We provide a structural characterization of graphs excluding an $\mathbb{S}^{\circ}_0$-embeddable graph as a minor.…

Combinatorics · Mathematics 2025-06-18 Laure Morelle , Evangelos Protopapas , Dimitrios M. Thilikos , Sebastian Wiederrecht

We show that a large class of right-angled Artin groups (in particular, those with planar complementary defining graph) can be embedded quasi-isometrically in pure braid groups and in the group of area preserving diffeomorphisms of the disk…

Geometric Topology · Mathematics 2016-09-07 John Crisp , Bert Wiest

A connected graph $G$ with at least $2m+2n+2$ vertices is said to have property $E(m,n)$ if, for any two disjoint matchings $M$ and $N$ of size $m$ and $n$ respectively, $G$ has a perfect matching $F$ such that $M\subseteq F$ and $N\cap…

Combinatorics · Mathematics 2010-02-04 Qiuli Li , Heping Zhang

Indyk and Sidiropoulos (2007) proved that any orientable graph of genus $g$ can be probabilistically embedded into a graph of genus $g-1$ with constant distortion. Viewing a graph of genus $g$ as embedded on the surface of a sphere with $g$…

Computational Geometry · Computer Science 2010-03-09 Glencora Borradaile , James R. Lee , Anastasios Sidiropoulos

We show that the asymptotic dimension of a hyperbolic relatively hyperbolic graph is finite provided that this holds true uniformly for the peripheral subgraphs and for the electrifiation. We use this to show that the asymptotic dimension…

Geometric Topology · Mathematics 2019-03-20 Ursula Hamenstaedt

This paper is the second in a series where we attempt to give a complete description of the space of all embedded minimal surfaces of fixed genus in a fixed (but arbitrary) closed 3-manifold. The key for understanding such surfaces is to…

Analysis of PDEs · Mathematics 2007-05-23 Tobias H. Colding , William P. Minicozzi

Ozkan et al. conjectured that any packing of $n$ spheres with generic radii will be stress-free, and hence will have at most $3n-6$ contacts. In this paper we prove that this conjecture is true for any sphere packing with contact graph of…

Combinatorics · Mathematics 2024-01-04 Sean Dewar

A signed graph is one that features two types of edges: positive and negative. Balanced signed graphs are those in which all cycles contain an even number of positive edges. In the adjacency matrix of a signed graph, entries can be $0$,…

Combinatorics · Mathematics 2024-08-15 Cristian M. Conde , Ezequiel Dratman , Luciano N. Grippo

We work with combinatorial maps to represent graph embeddings into surfaces up to isotopy. The surface in which the graph is embedded is left implicit in this approach. The constructions herein are proof-relevant and stated with a subset of…

Logic in Computer Science · Computer Science 2021-12-20 Jonathan Prieto-Cubides

Given a $d$-dimensional manifold $M$ and a knotted sphere $s\colon\mathbb{S}^{k-1}\hookrightarrow\partial M$ with $1\leq k\leq d$, for which there exists a framed dual sphere $G\colon\mathbb{S}^{d-k}\hookrightarrow\partial M$, we show that…

Geometric Topology · Mathematics 2025-10-08 Danica Kosanović , Peter Teichner

A graph G is a (Euclidean) unit disk graph if it is the intersection graph of unit disks in the Euclidean plane $\mathbb{R}^2$. Recognizing them is known to be $\exists\mathbb{R}$-complete, i.e., as hard as solving a system of polynomial…

Computational Geometry · Computer Science 2023-01-16 Nicholas Bieker , Thomas Bläsius , Emil Dohse , Paul Jungeblut

We resolve in the affirmative conjectures of Repovs and A. Skopenkov (1998), and M. Skopenkov (2003) generalizing the classical Hanani-Tutte theorem to the setting of approximating maps of graphs on 2-dimensional surfaces by embeddings. Our…

Computational Geometry · Computer Science 2022-08-31 Radoslav Fulek , Jan Kynčl

Let $P$ be a set of $n\geq 2$ points in general position in $R^2$. The edge disjointness graph $D(P)$ of $P$ is the graph whose vertices are all the closed straight line segments with endpoints in $P$, two of which are adjacent in $D(P)$ if…

Combinatorics · Mathematics 2023-04-07 J. Leaños , Christophe Ndjatchi , L. M. Ríos-Castro

We explore several families of flip-graphs, all related to polygons or punctured polygons. In particular, we consider the topological flip-graphs of once-punctured polygons which, in turn, contain all possible geometric flip-graphs of…

Combinatorics · Mathematics 2018-09-10 Hugo Parlier , Lionel Pournin

We prove that for any six points on the Riemann sphere there exist three disjoint closed (or open) discs, each of which contains exactly two of the six distinguished points. This statement shows that recently proposed method to numerically…

Complex Variables · Mathematics 2026-04-02 Matvey Smirnov

We prove that the ends of a properly immersed simply or one connected minimal surface in H(2)xR contained in a slab of height less than \pi of H(2)xR, are multi-graphs. When such a surface is embedded then the ends are graphs. When embedded…

Differential Geometry · Mathematics 2013-04-09 Pascal Collin , Laurent Hauswirth , Harold Rosenberg

This article focuses on a class of properly edge-colored graphs, which arise from topological combinatorics, and investigates their embeddings onto surfaces. Specifically, these graphs are known as the dual graphs of balanced normal…

Geometric Topology · Mathematics 2025-12-03 Biplab Basak , Sourav Sarkar