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Assume $L$ is a $k$-assignment of a graph $G$. An $L$-packing $\phi$ of $G$ is a sequence $\phi=(\phi_1, \ldots, \phi_k)$ of $k$-mappings such that each $\phi_i$ is an $L$-coloring of $G$, and for each vertex $v$ of $G$, $\{\phi_1(v),…

Combinatorics · Mathematics 2026-03-30 Masaki Kashima , Shun-ichi Maezawa , Xuding Zhu

Let $\mathcal G$ be a separable family of graphs. Then for all positive constants $\epsilon$ and $\Delta$ and for every sufficiently large integer $n$, every sequence $G_1,\dotsc,G_t\in\mathcal G$ of graphs of order $n$ and maximum degree…

Combinatorics · Mathematics 2016-06-01 Asaf Ferber , Choongbum Lee , Frank Mousset

Let $G=(V(G),E(G))$ be a simple graph. A non-empty set $S\subseteq V (G)$ is a weakly connected dominating set in $G$, if the subgraph obtained from $G$ by removing all edges each joining any two vertices in $V (G)\setminus S$ is connected.…

Combinatorics · Mathematics 2017-03-06 Saeid Alikhani , Somayeh Jahari , Mohammad Mehryar

For any graph $G$ of order $p$, a bijection $f: V(G)\to [1,p]$ is called a numbering of the graph $G$ of order $p$. The strength $str_f(G)$ of a numbering $f: V(G)\to [1,p]$ of $G$ is defined by $str_f(G) = \max\{f(u)+f(v)\; |\; uv\in…

Combinatorics · Mathematics 2021-03-02 Zhen-Bin Gao , Gee-Choon Lau , Wai-Chee Shiu

Given a family $\mathcal{H}$ of graphs, a graph $G$ is called $\mathcal{H}$-universal if $G$ contains every graph of $\mathcal{H}$ as a subgraph. Following the extensive research on universal graphs of small size for bounded-degree graphs,…

Combinatorics · Mathematics 2023-09-12 Peter Allen , Julia Böttcher , Anita Liebenau

Let $G$ be a connected simple graph on $n$ vertices and $m$ edges. Denote $N_{i}^{(j)}(G)$ the number of spanning subgraphs of $G$ having precisely $i$ edges and not more than $j$ connected components. The graph $G$ is \emph{strong} if…

Combinatorics · Mathematics 2024-12-31 Pablo Romero

Let $\mathcal{F}$ be a set of subsets of a set $W$. When is there a tree $T$ with vertex set $W$ such that each member of $\mathcal{F}$ is the set of vertices of a subtree of $T$? It is necessary that $\mathcal{F}$ has the Helly property…

Combinatorics · Mathematics 2025-06-05 Maria Chudnovsky , Tung Nguyen , Alex Scott , Paul Seymour

A set of vertices $X$ of a graph $G$ is a strong edge geodetic set if to any pair of vertices from $X$ we can assign one (or zero) shortest path between them such that every edge of $G$ is contained in at least one on these paths. The…

Combinatorics · Mathematics 2023-12-19 Sandi Klavžar , Eva Zmazek

Let $G=(V,E)$ be a connected graph. A vertex $w\in V$ distinguishes two elements (vertices or edges) $x,y\in E\cup V$ if $d_G(w,x)\ne d_G(w,y)$. A set $S$ of vertices in a connected graph $G$ is a mixed metric generator for $G$ if every two…

Combinatorics · Mathematics 2016-11-28 Aleksander Kelenc , Dorota Kuziak , Andrej Taranenko , Ismael G. Yero

Let $\mathcal{S}$ be a fixed family of graphs on vertex set $V$ and $\mathcal{G}$ be a collection of elements in $\mathcal{S}$. We investigated the transversal problem of finding the maximum value of $|\mathcal{G}|$ when $\mathcal{G}$…

Combinatorics · Mathematics 2023-10-11 Ethan Y. H. Li , Luyi Li , Ping Li

A \textit{maximum stable set} in a graph $G$ is a stable set of maximum cardinality. $S$ is a \textit{local maximum stable set} of $G$, and we write $S\in\Psi(G)$, if $S$ is a maximum stable set of the subgraph induced by $S\cup N(S)$,…

Discrete Mathematics · Computer Science 2010-08-18 Vadim E. Levit , Eugen Mandrescu

For a graph $G = (V, E)$, the $\gamma$-graph of $G$, denoted $G(\gamma) = (V(\gamma), E(\gamma))$, is the graph whose vertex set is the collection of minimum dominating sets, or $\gamma$-sets of $G$, and two $\gamma$-sets are adjacent in…

Combinatorics · Mathematics 2019-07-31 Stephen Finbow , Christopher M. van Bommel

The problem of finding the maximum-weight, planar subgraph of a finite, simple graph with nonnegative real edge weights is well known in industrial and electrical engineering, systems biology, sociology and finance. As the problem is known…

Discrete Mathematics · Computer Science 2017-12-18 Diane Castonguay , Elisângela Silva Dias , Leslie Richard Foulds

A set $D \subseteq V$ of a graph $G=(V, E)$ is a dominating set of $G$ if each vertex $v\in V\setminus D$ is adjacent to at least one vertex in $D,$ whereas a set $D_2\subseteq V$ is a $2$-dominating (double dominating) set of $G$ if each…

Computational Complexity · Computer Science 2023-12-05 Soumyashree Rana , Sounaka Mishra , Bhawani Sankar Panda

In a directed graph $D$, a vertex subset $S\subseteq V$ is a total dominating set if every vertex of $D$ has an in-neighbor from $S$. A total dominating set exists if and only if every vertex has at least one in-neighbor. We call the…

Combinatorics · Mathematics 2024-11-08 Zoltán L. Blázsik , Leila Vivien Nagy

A weighing matrix $W$ is quasi-balanced if $|W||W|^\top=|W|^\top|W|$ has at most two off-diagonal entries, where $|W|_{ij}=|W_{ij}|$. A quasi-balanced weighing matrix $W$ signs a strongly regular graph if $|W|$ coincides with its adjacency…

Combinatorics · Mathematics 2022-02-04 Hadi Kharaghani , Thomas Pender , Sho Suda

A graph is well-covered if all its maximal independent sets are of the same size (M. D. Plummer, 1970). A well-covered graph is 1-well-covered if the deletion of every vertex leaves a graph which is well-covered as well (J. W. Staples,…

Combinatorics · Mathematics 2016-12-13 Vadim E. Levit , Eugen Mandrescu

Designing well-connected graphs is a fundamental problem that frequently arises in various contexts across science and engineering. The weighted number of spanning trees, as a connectivity measure, emerges in numerous problems and plays a…

Data Structures and Algorithms · Computer Science 2016-04-13 Kasra Khosoussi , Gaurav S. Sukhatme , Shoudong Huang , Gamini Dissanayake

A fundamental and challenging problem in spectral graph theory is to characterize which graphs are uniquely determined by their spectra. In Wang [J. Combin. Theory, Ser. B, 122 (2017): 438-451], the author proved that an $n$-vertex graph…

Combinatorics · Mathematics 2024-10-04 Wei Wang , Wei Wang , Fuhai Zhu

Let $G$ be a connected graph. A vertex $w$ strongly resolves a pair $u$, $v$ of vertices of $G$ if there exists some shortest $u-w$ path containing $v$ or some shortest $v-w$ path containing $u$. A set $W$ of vertices is a strong resolving…

Combinatorics · Mathematics 2013-09-04 Dorota Kuziak , Ismael G. Yero , Juan A. Rodríguez-Velázquez