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A squaregraph is a plane graph in which each internal face is a $4$-cycle and each internal vertex has degree at least 4. This paper proves that every squaregraph is isomorphic to a subgraph of the semi-strong product of an outerplanar…

Combinatorics · Mathematics 2022-03-09 Robert Hickingbotham , Paul Jungeblut , Laura Merker , David R. Wood

In this paper, we introduce the graph $G(S)$ of a bounded semilattice $S$, which is a generalization of the intersection graph of the substructures of an algebraic structure. We prove some general theorems about these graphs; as an example,…

Combinatorics · Mathematics 2020-03-10 Parastoo Malakooti Rad , Peyman Nasehpour

Let $G$ be a graph, and $v\in V(G)$ and $S\subseteq V(G)\backslash v$ of size at least $k$. An important result on graph connectivity due to Perfect states that, if $v$ and $S$ are $k$-linked, then a $(k-1)$-link between a vertex $v$ and…

Combinatorics · Mathematics 2019-03-07 Ervin Győri , Michael D. Plummer , Dong Ye , Xiaoya Zha

Suppose that $A$ is a convex body in the plane and that $A_1,\dots,A_n$ are translates of $A$. Such translates give rise to an intersection graph of $A$, $G=(V,E)$, with vertices $V=\{1,\dots,n\}$ and edges $E=\{uv\mid A_u\cap A_v\neq…

Computational Geometry · Computer Science 2019-02-06 Anders Aamand , Mikkel Abrahamsen , Jakob Bæk Tejs Knudsen , Peter Michael Reichstein Rasmussen

Let $\mathcal{H}$ be a class of given graphs. A graph $G$ is said to be $\mathcal{H}$-free if $G$ contains no induced copies of $H$ for any $H \in \mathcal{H}$. In this article, we characterize all pairs $\{R,S\}$ of graphs such that every…

Combinatorics · Mathematics 2017-11-27 Junfeng Du , Ziwen Huang , Liming Xiong

Using the Semple bundle construction, we derive an intersection-theoretic formula for the number of simultaneous contacts of specified orders between members of a generic family of degree $d$ plane curves and finitely many fixed curves. The…

alg-geom · Mathematics 2008-02-03 Susan Jane Colley , Gary Kennedy

Weak unit disk contact graphs are graphs that admit representing nodes as a collection of internally disjoint unit disks whose boundaries touch if there is an edge between the corresponding nodes. In this work we focus on graphs without…

Computational Geometry · Computer Science 2020-10-06 Jonas Cleve

In this paper we study properties of intersection graphs of k-bend paths in the rectangular grid. A k-bend path is a path with at most k 90 degree turns. The class of graphs representable by intersections of k-bend paths is denoted by…

Computational Geometry · Computer Science 2012-06-25 Steven Chaplick , Vít Jelínek , Jan Kratochvíl , Tomáš Vyskočil

In this article we introduce and study the intersection graph of graded ideals of graded rings. The intersection graph of $G-$graded ideals of a graded ring $(R,G)$ is a simple graph, denoted by $Gr_G(R)$, whose vertices are the nontrivial…

Rings and Algebras · Mathematics 2020-08-11 T. Alraqad , H. Saber , R. Abu-Dawwas

Two graphs are homomorphism indistinguishable over a graph class $\mathcal{F}$, denoted by $G \equiv_{\mathcal{F}} H$, if $\operatorname{hom}(F,G) = \operatorname{hom}(F,H)$ for all $F \in \mathcal{F}$ where $\operatorname{hom}(F,G)$…

Combinatorics · Mathematics 2023-07-11 Daniel Neuen

We undertake a comprehensive study of structural properties of graph products of von Neumann algebras equipped with faithful, normal states, as well as properties of the graph products relative to subalgebras coming from induced subgraphs.…

In this paper we investigate the connectedness and the isomorphism problems for zig-zag products of two graphs. A sufficient condition for the zig-zag product of two graphs to be connected is provided, reducing to the study of the…

Combinatorics · Mathematics 2017-03-10 Daniele D'Angeli , Alfredo Donno , Ecaterina Sava-Huss

Given a collection of graphs $\mathbf{G}=(G_1, \ldots, G_m)$ with the same vertex set, an $m$-edge graph $H\subset \cup_{i\in [m]}G_i$ is a transversal if there is a bijection $\phi:E(H)\to [m]$ such that $e\in E(G_{\phi(e)})$ for each…

Combinatorics · Mathematics 2022-05-04 Richard Montgomery , Alp Müyesser , Yanitsa Pehova

We investigate edge-intersection graphs of paths in the plane grid, regarding a parameter called the bend-number. I.e., every vertex is represented by a grid path and two vertices are adjacent if and only if the two grid paths share at…

Combinatorics · Mathematics 2012-08-21 Daniel Heldt , Kolja Knauer , Torsten Ueckerdt

It is known that the class of all graphs not containing a graph $H$ as an induced subgraph is cop-bounded if and only if $H$ is a forest whose every component is a path. In this study, we characterize all sets $\mathscr{H}$ of graphs with…

Combinatorics · Mathematics 2020-07-14 Masood Masjoody , Ladislav Stacho

A mapping $\alpha : V(G) \to V(H)$ from the vertex set of one graph $G$ to another graph $H$ is an isometric embedding if the shortest path distance between any two vertices in $G$ equals the distance between their images in $H$. Here, we…

Discrete Mathematics · Computer Science 2021-12-21 Joseph Berleant , Kristin Sheridan , Anne Condon , Virginia Vassilevska Williams , Mark Bathe

For any particular class of graphs, algorithms for computational problems restricted to the class often rely on structural properties that depend on the specific problem at hand. This begs the question if a large set of such results can be…

Let $D$ be a division ring, $n$ a positive integer, and GL$_n(D)$ the general linear group of degree $n$ over $D$. In this paper, we study the induced subgraph of the intersection graph of GL$_n(D)$ generated by all non-trivial proper…

Rings and Algebras · Mathematics 2020-02-18 Bui Xuan Hai , Binh-Minh Bui-Xuan , Le Van Chua , Mai Hoang Bien

The $\gamma$-graph of a graph $G$ is the graph whose vertices are labelled by the minimum dominating sets of $G$, in which two vertices are adjacent when their corresponding minimum dominating sets (each of size $\gamma(G)$) intersect in a…

Combinatorics · Mathematics 2020-04-06 Matt DeVos , Adam Dyck , Jonathan Jedwab , Samuel Simon

A simple topological graph $G$ is a graph drawn in the plane so that any pair of edges have at most one point in common, which is either an endpoint or a proper crossing. $G$ is called saturated if no further edge can be added without…

Combinatorics · Mathematics 2015-01-30 Jan Kynčl , János Pach , Radoš Radoičić , Géza Tóth
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