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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

This paper introduces a geometric representation of hypergraphs by representing hyperedges as simplices. Building on this framework, we employ homotopy groups to analyze the topological structure of hypergraphs embedded in high-dimensional…

Combinatorics · Mathematics 2025-11-14 Qiming Fang , Sihong Shao

A graph is called (generically) rigid in R^d if, for any choice of sufficiently generic edge lengths, it can be embedded in R^d in a finite number of distinct ways, modulo rigid transformations. Here, we deal with the problem of determining…

Computational Geometry · Computer Science 2014-10-24 Stylianos C. Despotakis , Ioannis Z. Emiris

A set W \subseteq V (G) is called a resolving set, if for each pair of distinct vertices u,v \in V (G) there exists t \in W such that d(u,t) \neq d(v,t), where d(x,y) is the distance between vertices x and y. The cardinality of a minimum…

Combinatorics · Mathematics 2015-09-08 Ali Behtoei , Akbar Davoodi , Mohsen Jannesari , Behnaz Omoomi

An EPG-representation of a graph $G$ is a collection of paths in a plane square grid, each corresponding to a single vertex of $G$, so that two vertices are adjacent if and only if their corresponding paths share infinitely many points. In…

Discrete Mathematics · Computer Science 2017-11-15 Martin Pergel , Paweł Rzążewski

An obstacle representation of a graph is a mapping of the vertices onto points in the plane and a set of connected regions of the plane (called obstacles) such that the straight-line segment connecting the points corresponding to two…

Bidirected graphs are a generalisation of directed graphs that arises in the study of undirected graphs with perfect matchings. Menger's famous theorem - the minimum size of a set separating two vertex sets $X$ and $Y$ is the same as the…

Combinatorics · Mathematics 2023-06-29 Nathan Bowler , Ebrahim Ghorbani , Florian Gut , Raphael W. Jacobs , Florian Reich

The metric dimension of a graph is the smallest number of nodes required to identify all other nodes based on shortest path distances uniquely. Applications of metric dimension include discovering the source of a spread in a network,…

Combinatorics · Mathematics 2021-04-16 Richard C. Tillquist , Rafael M. Frongillo , Manuel E. Lladser

For an ordered set W = {w1,w2,...,wk} of vertices and a vertex v in a connected graph G, the ordered k-vector r(v|W) := (d(v,w1),d(v,w2),...,d(v,wk)) is called the (metric) representation of v with respect to W, where d(x,y) is the distance…

Combinatorics · Mathematics 2022-02-03 Mohsen Jannesari

Let $\mathcal{A}$ be a set of positive numbers. A graph $G$ is called an $\mathcal{A}$-embeddable graph in $\mathbb{R}^d$ if the vertices of $G$ can be positioned in $\mathbb{R}^d$ so that the distance between endpoints of any edge is an…

Computational Complexity · Computer Science 2017-10-17 Mikhail Tikhomirov

A segment representation of a graph is an assignment of line segments in 2D to the vertices in such a way that two segments intersect if and only if the corresponding vertices are adjacent. Not all graphs have such segment representations,…

Computational Geometry · Computer Science 2018-10-17 Therese Biedl

Let $U_\epsilon(\mathfrak g)$ be the simply connected quantized enveloping algebra associated to a finite-dimensional complex simple Lie algebra $\mathfrak g$ at the roots of unity. The De Concini-Kac-Procesi conjecture on the dimension of…

Quantum Algebra · Mathematics 2007-05-23 Nicoletta Cantarini , Giovanna Carnovale , Mauro Costantini

Statistical analysis of a graph often starts with embedding, the process of representing its nodes as points in space. How to choose the embedding dimension is a nuanced decision in practice, but in theory a notion of true dimension is…

Machine Learning · Statistics 2021-01-06 Patrick Rubin-Delanchy

An embedding of a metric graph $(G, d)$ on a closed hyperbolic surface is \emph{essential}, if each complementary region has a negative Euler characteristic. We show, by construction, that given any metric graph, its metric can be rescaled…

Geometric Topology · Mathematics 2019-05-22 Bidyut Sanki

Let G be a graph with undirected and directed edges. Its representation is given by assigning a vector space to each vertex, a bilinear form on the corresponding vector spaces to each directed edge, and a linear map to each directed edge.…

Representation Theory · Mathematics 2019-03-26 Abdullah Alazemi , Milica Anđelić , Carlos M. da Fonseca , Vladimir V. Sergeichuk

Graph embeddings, wherein the nodes of the graph are represented by points in a continuous space, are used in a broad range of Graph ML applications. The quality of such embeddings crucially depends on whether the geometry of the space…

Machine Learning · Statistics 2022-02-03 Francesco Di Giovanni , Giulia Luise , Michael Bronstein

A subset $X$ of vertices in a graph $G$ is a {\em diameter 2 subset} if the distance of any two vertices of $X$ is at most two {\em in $G[X]$}. Relaxing this notion, a subset $X$ of vertices in a graph $G$ is a {\em 2-reachable subset} if…

Combinatorics · Mathematics 2025-06-16 Andras Gyarfas , Gabor N. Sarkozy

A unit cube in $k$ dimensional space (or \emph{$k$-cube} in short) is defined as the Cartesian product $R_1\times R_2\times...\times R_k$ where $R_i$(for $1\leq i\leq k$) is a closed interval of the form $[a_i,a_i+1]$ on the real line. A…

Discrete Mathematics · Computer Science 2008-03-26 L. Sunil Chandran , Mathew C. Francis , Naveen Sivadasan

A set $W\subseteq V(G)$ is called a resolving set for $G$, if for each two distinct vertices $u,v\in V(G)$ there exists $w\in W$ such that $d(u,w)\neq d(v,w)$, where $d(x,y)$ is the distance between the vertices $x$ and $y$. The minimum…

Combinatorics · Mathematics 2012-03-13 Mohsen Jannesari

Consider a finite dimensional real vector space and a finite group acting unitarily on it. We study the general problem of constructing Euclidean stable embeddings of the quotient space of orbits. Our embedding is based on subsets of sorted…

Representation Theory · Mathematics 2025-08-18 Radu Balan , Efstratios Tsoukanis