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A total coloring of a graph $G$ is a coloring of its vertices and edges such that no adjacent vertices, edges, and no incident vertices and edges obtain the same color. An interval total $t$-coloring of a graph $G$ is a total coloring of…

Combinatorics · Mathematics 2014-08-12 Petros A. Petrosyan , Nerses A. Khachatryan

Zero forcing is a graph propagation process for which vertices fill-in (or propagate information to) neighbor vertices if all neighbors except for one, are filled. The zero-forcing number is the smallest number of vertices that must be…

Combinatorics · Mathematics 2024-10-24 Heather LeClair , Tim Spilde , Sarah Anderson , Brenda Kroschel

Zero forcing is a graph coloring process that is used to model spreading phenomena in real-world scenarios. It can also be viewed as a single-player combinatorial game on a graph, where the player's goal is to select a subset of vertices of…

Combinatorics · Mathematics 2025-09-05 Aida Abiad , Maryam Moghaddas

We define a $P$-compelling coloring as a proper coloring of the vertices of a graph such that every subset consisting of one vertex of each color has property $P$. The $P$-compelling chromatic number is the minimum number of colors in such…

Combinatorics · Mathematics 2021-05-11 Anna Bachstein , Wayne Goddard , Michael A. Henning , John Xue

The domination multisubdivision number of a nonempty graph $G$ was defined as the minimum positive integer $k$ such that there exists an edge which must be subdivided $k$ times to increase the domination number of $G$. Similarly we define…

Combinatorics · Mathematics 2013-09-30 Diana Avella-Alaminos , Magda Dettlaff , Magdalena Lemańska , Rita Zuazua

Let $G$ be a graph. The maximum nullity of $G$, denoted by $M(G)$, is defined to be the largest possible nullity over all real symmetric matrices $A$ whose $a_{ij}\neq 0$ for $i\neq j$, whenever two vertices $u_i$ and $u_j$ of $G$ are…

Combinatorics · Mathematics 2017-05-30 Saieed Akbari , Ebrahim Vatandoost , Yasser Golkhandy Pour

A total labeling of a graph $G = (V, E)$ is said to be local total antimagic if it is a bijection $f: V\cup E \to\{1,\ldots ,|V|+|E|\}$ such that adjacent vertices, adjacent edges, and incident vertex and edge have distinct induced weights…

Combinatorics · Mathematics 2024-07-02 G. C. Lau

For a family $\mathcal{H}$ of graphs, a graph $G$ is said to be {\it $\mathcal{H}$-free} if $G$ contains no member of $\mathcal{H}$ as an induced subgraph. We let $\tilde{\mathcal{G}}_{3}(\mathcal{H})$ denote the family of connected…

Combinatorics · Mathematics 2024-04-18 Yoshimi Egawa , Michitaka Furuya

Given a multigraph $G$ and function $f : V(G) \rightarrow \mathbb{Z}_{\ge 2}$ on its vertices, a degree-$f$ subgraph of $G$ is a spanning subgraph in which every vertex $v$ has degree at most $f(v)$. The degree-$f$ arboricity $a_f(G)$ of…

Combinatorics · Mathematics 2023-01-25 Ronen Wdowinski

We solve a conjecture by Becker et al. (arXiv:2404.05963) on the topic of zero forcing regarding the number of minimal forts of a tree. They conjectured and we prove $\mathcal{F}_{T_n} \le \binom{n}{2} \mathcal{F}_{P_n}$ where…

Combinatorics · Mathematics 2026-05-11 Nguyen Hoang Dat , Franklin H. J. Kenter

An equitable coloring is a proper coloring of a graph such that the sizes of the color classes differ by at most one. A graph $G$ is equitably $k$-colorable if there exists an equitable coloring of $G$ which uses $k$ colors, each one…

Combinatorics · Mathematics 2018-03-21 Hemanshu Kaul , Jeffrey A. Mudrock , Michael J. Pelsmajer

In 2018, the concept of a fort in graph theory was introduced as a non-empty subset of vertices satisfying the condition that no vertex outside the set has exactly one neighbor in the set. Since then, forts have played a significant role in…

Combinatorics · Mathematics 2026-03-12 Thomas R. Cameron , Kelvin Li

We consider (not necessarily proper) colorings of the vertices of a graph where every color is thoroughly distributed, that is, appears in every open neighborhood. Equivalently, every color is a total dominating set. We define $\td(G)$ as…

Combinatorics · Mathematics 2016-10-03 Wayne Goddard , Michael A. Henning

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

In this paper we begin the study of well-failed graphs, that is, graphs in which every maximal failed zero forcing set is a maximum failed zero forcing set, or equivalently, in which every minimal fort is a minimum fort. We characterize…

Combinatorics · Mathematics 2025-02-03 Bonnie Jacob

Zero forcing is a deterministic iterative graph coloring process in which vertices are colored either blue or white, and in every round, any blue vertices that have a single white neighbor force these white vertices to become blue. Here we…

Combinatorics · Mathematics 2019-09-17 Sean English , Calum MacRury , Pawel Pralat

In this paper, we study a parameter that is squeezed between arguably the two important domination parameters, namely the domination number, $\gamma(G)$, and the total domination number, $\gamma_t(G)$. A set $S$ of vertices in $G$ is a…

Combinatorics · Mathematics 2023-06-22 Wei Zhuang , Guoliang Hao

The forcing number of a perfect matching $M$ in a graph $G$ is the smallest number of edges inside $M$ that can not be contained in other perfect matchings. The anti-forcing number of $M$ is the smallest number of edges outside $M$ whose…

Combinatorics · Mathematics 2020-12-25 Kai Deng , Huazhong Lü , Tingzeng Wu

The Total Colouring Conjecture suggests that $\Delta+3$ colours ought to suffice in order to provide a proper total colouring of every graph $G$ with maximum degree $\Delta$. Thus far this has been confirmed up to an additive constant…

Combinatorics · Mathematics 2017-03-02 Jakub Przybyło

The Graceful Tree Conjecture of Rosa from 1967 asserts that the vertices of each tree T of order n can be injectively labelled by using the numbers {1,2,...,n} in such a way that the absolute differences induced on the edges are pairwise…

Combinatorics · Mathematics 2020-06-23 Anna Adamaszek , Peter Allen , Codrut Grosu , Jan Hladky