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The pathwidth of a graph $G$ is the smallest $w\in \mathbb{N}$ such that $G$ can be constructed from a sequence of graphs, each on at most $w+1$ vertices, by gluing them together in a linear fashion. We provide a full classification of the…

Combinatorics · Mathematics 2024-12-30 Maria Chudnovsky , Sepehr Hajebi , Sophie Spirkl

For a graph class $\mathcal{G}$, we define the $\mathcal{G}$-modular cardinality of a graph $G$ as the minimum size of a vertex partition of $G$ into modules that each induces a graph in $\mathcal{G}$. This generalizes other module-based…

Computational Complexity · Computer Science 2023-07-06 Manuel Lafond , Weidong Luo

We introduce a family of graph parameters, called induced multipartite graph parameters, and study their computational complexity. First, we consider the following decision problem: an instance is an induced multipartite graph parameter $p$…

Computational Complexity · Computer Science 2023-05-05 Ryan L. Mann , Luke Mathieson , Catherine Greenhill

We generalize two results about subgroups of multiplicative group of finite field of prime order. In particular, the lower bound on the cardinality of the set of values of polynomial $P(x,y)$ is obtained under the certain conditions, if…

Combinatorics · Mathematics 2020-08-21 Sofia Aleshina , Ilya Vyugin

An ordered graph $\mathcal{G}$ is a simple graph together with a total ordering on its vertices. The (2-color) Ramsey number of $\mathcal{G}$ is the smallest integer $N$ such that every 2-coloring of the edges of the complete ordered graph…

Combinatorics · Mathematics 2019-02-26 Jesse Geneson , Amber Holmes , Xujun Liu , Dana Neidinger , Yanitsa Pehova , Isaac Wass

Given a graph $G=(V,E)$, a subset $X$ of $V$ is an interval of $G$ provided that for any $a, b\in X$ and $ x\in V \setminus X$, $\{a,x\}\in E$ if and only if $\{b,x\}\in E$. For example, $\emptyset$, $\{x\}(x\in V)$ and $V$ are intervals of…

Combinatorics · Mathematics 2013-08-15 Rim Ben Hamadou , Imed Boudabbous

Let $F$, $G$ and $H$ be simple graphs. We say $F \rightarrow (G, H)$ if for every $2$-coloring of the edges of $F$ there exists a monochromatic $G$ or $H$ in $F$. The Ramsey number $r(G, H)$ is defined as $r(G, H) = min\{|V (F)|: F…

Combinatorics · Mathematics 2018-11-22 Joanna Cyman , Tomasz Dzido

The detour order of a graph $G$, denoted $\tau(G)$, is the order of a longest path in $G$. A partition $(A, B)$ of $V(G)$ such that $\tau(\langle A \rangle) \leq a$ and $\tau(\langle B \rangle) \leq b$ is called an $(a, b)$-partition of…

Combinatorics · Mathematics 2014-09-16 G. Sethuraman

A partial orientation $\vec{H}$ of a graph $G$ is a weak $r$-guidance system if for any two vertices at distance at most $r$ in $G$, there exists a shortest path $P$ between them such that $\vec{H}$ directs all but one edge in $P$ towards…

Data Structures and Algorithms · Computer Science 2022-10-18 Zdeněk Dvořák

For a (possibly infinite) fixed family of graphs F, we say that a graph G overlays F on a hypergraph H if V(H) is equal to V(G) and the subgraph of G induced by every hyperedge of H contains some member of F as a spanning subgraph.While it…

Data Structures and Algorithms · Computer Science 2017-03-16 Nathann Cohen , Frédéric Havet , Dorian Mazauric , Ignasi Sau , Rémi Watrigant

Given a graph $H$, let $\chi_H(\mathbb{R}^n)$ be the smallest positive integer $r$ such that there exists an $r$-coloring of $\mathbb{R}^n$ with no monochromatic unit-copy of $H$, that is a set of $|V(H)|$ vertices of the same color such…

Combinatorics · Mathematics 2025-12-19 Maria Axenovich , Dingyuan Liu , Arsenii Sagdeev

For given graphs $G$ and $H,$ the \emph{Ramsey number} $R(G,H)$ is the least natural number $n$ such that for every graph $F$ of order $n$ the following condition holds: either $F$ contains $G$ or the complement of $F$ contains $H.$ In this…

Combinatorics · Mathematics 2008-05-13 Kashif Ali , Edy Tri Baskoro , Ioan Tomescu

Given a graph $G$ and assuming that some vertices of $G$ are infected, the $r$-neighbor bootstrap percolation rule makes an uninfected vertex $v$ infected if $v$ has at least $r$ infected neighbors. The $r$-percolation number, $m(G, r)$, of…

Combinatorics · Mathematics 2025-06-24 Boštjan Brešar , Jaka Hedžet , Michael A. Henning

A dominating set of a graph $G$ is a set $D\subseteq V_G$ such that every vertex in $V_G-D$ is adjacent to at least one vertex in $D$, and the domination number $\gamma(G)$ of $G$ is the minimum cardinality of a dominating set of $G$. A set…

Combinatorics · Mathematics 2021-01-18 Andrzej Lingas , Mateusz Miotk , Jerzy Topp , Paweł Żyliński

A set $S$ of vertices in a graph $G$ is a dominating set if every vertex of $V(G) \setminus S$ is adjacent to a vertex in $S$. A coalition in $G$ consists of two disjoint sets of vertices $X$ and $Y$ of $G$, neither of which is a dominating…

Combinatorics · Mathematics 2023-07-06 Davood Bakhshesh , Michael A. Henning

A dynamic coloring of the vertices of a graph $G$ starts with an initial subset $S$ of colored vertices, with all remaining vertices being non-colored. At each discrete time interval, a colored vertex with exactly one non-colored neighbor…

Combinatorics · Mathematics 2018-01-17 Randy Davila , Michael Henning

Let $G=(V,E)$ be a graph and $p$ be a positive integer. A subset $S\subseteq V$ is called a $p$-dominating set if each vertex not in $S$ has at least $p$ neighbors in $S$. The $p$-domination number $\g_p(G)$ is the size of a smallest…

Combinatorics · Mathematics 2012-04-19 You Lu , Fu-Tao Hu , Jun-Ming Xu

Let $H\xrightarrow{s} G$ denote that any edge-coloring of $H$ by $s$ colors contains a monochromatic $G$. The degree Ramsey number $r_{\Delta}(G;s)$ is defined to be $\min\{\Delta(H):H\xrightarrow{s} G\}$, and the degree bipartite Ramsey…

Combinatorics · Mathematics 2019-09-04 Ye Wang , Yusheng Li , Yan Li

Let $G$ be a graph with vertex set $V$ and of order $n = |V|$, and let $\delta(G)$ and $\Delta(G)$ be the minimum and maximum degree of $G$, respectively. Two disjoint sets $V_1, V_2 \subseteq V$ form a coalition in $G$ if none of them is a…

Discrete Mathematics · Computer Science 2022-11-03 Davood Bakhshesh , Michael A. Henning , Dinabandhu Pradhan

We say a graph has property $\mathcal{P}_{g,p}$ when it is an induced subgraph of the curve graph of a surface of genus $g$ with $p$ punctures. Two well-known graph invariants, the chromatic and clique numbers, can provide obstructions to…

Geometric Topology · Mathematics 2023-11-03 Edgar A. Bering , Gabriel Conant , Jonah Gaster
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