Radio antipodal colorings of graphs

Gary Chartrand; David Erwin; Ping Zhang

Displaying similar documents to “Radio antipodal colorings of graphs”

Set vertex colorings and joins of graphs

Futaba Okamoto, Craig W. Rasmussen, Ping Zhang (2009)

Czechoslovak Mathematical Journal

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For a nontrivial connected graph $G$ , let $c V (G) \to ℕ$ be a vertex coloring of $G$ where adjacent vertices may be colored the same. For a vertex $v$ of $G$ , the neighborhood color set $NC (v)$ is the set of colors of the neighbors of $v$ . The coloring $c$ is called a set coloring if $NC (u) \neq NC (v)$ for every pair $u, v$ of adjacent vertices of $G$ . The minimum number of colors required of such a coloring is called the set chromatic number $χ_{s} (G)$ . A study is made of the set chromatic number of the join $G + H$ of two graphs $G$ and $H$ . Sharp lower...

3-consecutive c-colorings of graphs

Csilla Bujtás, E. Sampathkumar, Zsolt Tuza, M.S. Subramanya, Charles Dominic (2010)

Discussiones Mathematicae Graph Theory

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A 3-consecutive C-coloring of a graph G = (V,E) is a mapping φ:V → ℕ such that every path on three vertices has at most two colors. We prove general estimates on the maximum number ${(χ ̅)}_{3 C C} (G)$ of colors in a 3-consecutive C-coloring of G, and characterize the structure of connected graphs with ${(χ ̅)}_{3 C C} (G) \geq k$ for k = 3 and k = 4.

Rainbow connection in graphs

Gary Chartrand, Garry L. Johns, Kathleen A. McKeon, Ping Zhang (2008)

Mathematica Bohemica

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Let $G$ be a nontrivial connected graph on which is defined a coloring $c E (G) \to {1, 2, ..., k}$ , $k \in ℕ$ , of the edges of $G$ , where adjacent edges may be colored the same. A path $P$ in $G$ is a rainbow path if no two edges of $P$ are colored the same. The graph $G$ is rainbow-connected if $G$ contains a rainbow $u - v$ path for every two vertices $u$ and $v$ of $G$ . The minimum $k$ for which there exists such a $k$ -edge coloring is the rainbow connection number $r c (G)$ of $G$ . If for every pair $u, v$ of distinct vertices, $G$ contains a rainbow $u - v$ geodesic,...

Radio k-colorings of paths

Gary Chartrand, Ladislav Nebeský, Ping Zhang (2004)

Discussiones Mathematicae Graph Theory

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For a connected graph G of diameter d and an integer k with 1 ≤ k ≤ d, a radio k-coloring of G is an assignment c of colors (positive integers) to the vertices of G such that d(u,v) + |c(u)- c(v)| ≥ 1 + k for every two distinct vertices u and v of G, where d(u,v) is the distance between u and v. The value rcₖ(c) of a radio k-coloring c of G is the maximum color assigned to a vertex of G. The radio k-chromatic number rcₖ(G) of G is the minimum value of rcₖ(c) taken over all radio k-colorings...

Hajós' theorem for list colorings of hypergraphs

Claude Benzaken, Sylvain Gravier, Riste Skrekovski (2003)

Discussiones Mathematicae Graph Theory

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A well-known theorem of Hajós claims that every graph with chromathic number greater than k can be constructed from disjoint copies of the complete graph $K_{k + 1}$ by repeated application of three simple operations. This classical result has been extended in 1978 to colorings of hypergraphs by C. Benzaken and in 1996 to list-colorings of graphs by S. Gravier. In this note, we capture both variations to extend Hajós’ theorem to list-colorings of hypergraphs.

Defining sets in (proper) vertex colorings of the Cartesian product of a cycle with a complete graph

D. Ali Mojdeh (2006)

Discussiones Mathematicae Graph Theory

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In a given graph G = (V,E), a set of vertices S with an assignment of colors to them is said to be a defining set of the vertex coloring of G, if there exists a unique extension of the colors of S to a c ≥ χ(G) coloring of the vertices of G. A defining set with minimum cardinality is called a minimum defining set and its cardinality is the defining number, denoted by d(G,c). The d(G = Cₘ × Kₙ, χ(G)) has been studied. In this note we show that the exact value of defining number d(G =...

Upper bounds on the b-chromatic number and results for restricted graph classes

Mais Alkhateeb, Anja Kohl (2011)

Discussiones Mathematicae Graph Theory

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A b-coloring of a graph G by k colors is a proper vertex coloring such that every color class contains a color-dominating vertex, that is, a vertex having neighbors in all other k-1 color classes. The b-chromatic number $χ_{b} (G)$ is the maximum integer k for which G has a b-coloring by k colors. Moreover, the graph G is called b-continuous if G admits a b-coloring by k colors for all k satisfying $χ (G) \leq k \leq χ_{b} (G)$ . In this paper, we establish four general upper bounds on $χ_{b} (G)$ . We present results on the b-chromatic...