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We say a proper coloring of a graph is distance-$k$ fall if every vertex is within distance $k$ of at least one vertex of every color. We show that if $G$ is a connected graph of order at least $3$ that is $3$-colorable, thenit has a…

Combinatorics · Mathematics 2025-09-01 Wayne Goddard , Sonwabile Mafunda

We prove that for any graph $G$, the total chromatic number of $G$ is at most $\Delta(G)+2\left\lceil \frac{|V(G)|}{\Delta(G)+1} \right\rceil$. This saves one color in comparison with a result of Hind from 1992. In particular, our result…

Combinatorics · Mathematics 2024-05-14 Aseem Dalal , Jessica McDonald , Songling Shan

A distinguishing colouring of a graph is a colouring of the vertex set such that no non-trivial automorphism preserves the colouring. Tucker conjectured that if every non-trivial automorphism of a locally finite graph moves infinitely many…

Combinatorics · Mathematics 2015-04-30 Florian Lehner , Rögnvaldur G. Möller

An acyclic edge coloring of a graph is a proper edge coloring without any bichromatic cycles. The acyclic chromatic index of a graph $G$ denoted by $a'(G)$, is the minimum $k$ such that $G$ has an acyclic edge coloring with $k$ colors.…

Combinatorics · Mathematics 2024-01-31 Nevil Anto , Manu Basavaraju , Suresh Manjanath Hegde , Shashanka Kulamarva

An \emph{interval $t$-coloring} of a multigraph $G$ is a proper edge coloring with colors $1,\dots,t$ such that the colors on the edges incident to every vertex of $G$ are colored by consecutive colors. A \emph{cyclic interval $t$-coloring}…

Combinatorics · Mathematics 2016-11-22 Carl Johan Casselgren , Hrant H. Khachatrian , Petros A. Petrosyan

An edge-coloring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Lehner, Pil\'{s}niak, and Stawiski proved that all connected regular graphs except $K_2$ admit an asymmetric edge-coloring with…

Combinatorics · Mathematics 2021-07-21 Mariusz Grech , Andrzej Kisielewicz

The distinguishing number $D(G)$ of a graph $G$ is the least integer $d$ such that $G$ has a vertex labeling with $d$ labels that is preserved only by a trivial automorphism. In this paper we characterize all trees with radius at most three…

Combinatorics · Mathematics 2016-11-29 Saeid Alikhani , Samaneh Soltani

A \emph{star coloring} of a graph $G$ is a proper vertex-coloring such that no path on four vertices is $2$-colored. The minimum number of colors required to obtain a star coloring of a graph $G$ is called star chromatic number and it is…

Combinatorics · Mathematics 2023-05-30 Harshit Kumar Choudhary , I. Vinod Reddy

A graph $G$ is 3-colorable if and only if it maps homomorphically to the complete 3-vertex graph $K_3$. The last condition can be checked by a $k$-consistency algorithm where the parameter $k$ has to be chosen large enough, dependent on…

Computational Complexity · Computer Science 2014-02-18 Albert Atserias , Anuj Dawar , Oleg Verbitsky

The $k$-dominating graph $D_k(G)$ of a graph $G$ is defined on the vertex set consisting of dominating sets of $G$ with cardinality at most $k$, two such sets being adjacent if they differ by either adding or deleting a single vertex. A…

Combinatorics · Mathematics 2016-04-26 Saeid Alikhani , Davood Fatehi , Sandi Klavžar

For an edge-colored graph $G$, we call an edge-cut $M$ of $G$ monochromatic if the edges of $M$ are colored with a same color. The graph $G$ is called monochromatically disconnected if any two distinct vertices of $G$ are separated by a…

Combinatorics · Mathematics 2019-11-05 Ping Li , Xueliang Li

We supply an upper bound on the distinguishing chromatic number of certain infinite graphs satisfying an adjacency property. Distinguishing proper $n$-colourings are generalized to the new notion of distinguishing homomorphisms. We prove…

Combinatorics · Mathematics 2013-09-03 Anthony Bonato , Dejan Delic

A graph is said to be interval colourable if it admits a proper edge-colouring using palette $\mathbb{N}$ in which the set of colours incident to each vertex is an interval. The interval colouring thickness of a graph $G$ is the minimum $k$…

An edge-colouring of a graph is distinguishing, if the only automorphism which preserves the colouring is the identity. It has been conjectured that all but finitely many connected, finite, regular graphs admit a distinguishing…

Combinatorics · Mathematics 2020-05-11 Florian Lehner , Monika Pilśniak , Marcin Stawiski

The distinguishing number $\operatorname D(G)$ of a graph $G$ is the least cardinal $d$ such that $G$ has a labeling with $d$ labels which is only preserved by the trivial automorphism. We show that the distinguishing number of infinite,…

Combinatorics · Mathematics 2013-11-19 Johannes Cuno , Wilfried Imrich , Florian Lehner

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. A graphoidal cover of $G$ is a…

Combinatorics · Mathematics 2017-08-22 Saeid Alikhani , Samaneh Soltani

An identifying open code of a graph $G$ is a set $S$ of vertices that is both a separating open code (that is, $N_G(u) \cap S \ne N_G(v) \cap S$ for all distinct vertices $u$ and $v$ in $G$) and a total dominating set (that is, $N(v) \cap S…

Combinatorics · Mathematics 2024-07-16 Dipayan Chakraborty , Florent Foucaud , Michael A. Henning

We say that a vertex or edge colouring of a graph is distinguishing if the only automorphism that preserves this colouring is the identity. A (proper) distinguishing colouring is irreducible if there is no possibility of merging two…

Combinatorics · Mathematics 2026-02-18 Marcin Stawiski

A $c$-labeling $\phi: V(G) \rightarrow \{1, 2, \hdots, c \}$ of graph $G$ is distinguishing if, for every non-trivial automorphism $\pi$ of $G$, there is some vertex $v$ so that $\phi(v) \neq \phi(\pi(v))$. The distinguishing number of $G$,…

Combinatorics · Mathematics 2023-08-29 Christine T. Cheng

The isolation number of a graph $G$ (also called the vertex-edge domination number of $G$), denoted by $\iota(G)$, is the size of a smallest subset $D$ of the vertex set $V(G)$ of $G$ such that $G-N[D]$ (the graph obtained by deleting the…

Combinatorics · Mathematics 2025-02-17 Peter Borg , Magdalena Lemańska , Mercè Mora , María José Souto-Salorio
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