Generalized Fractional and Circular Total Colorings of Graphs

Arnfried Kemnitz; Massimiliano Marangio; Peter Mihók; Janka Oravcová; Roman Soták

Displaying similar documents to “Generalized Fractional and Circular Total Colorings of Graphs”

Generalized Fractional Total Colorings of Graphs

Gabriela Karafová, Roman Soták (2015)

Discussiones Mathematicae Graph Theory

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Let P and Q be additive and hereditary graph properties and let r, s be integers such that r ≥ s. Then an r/s -fractional (P,Q)-total coloring of a finite graph G = (V,E) is a mapping f, which assigns an s-element subset of the set {1, 2, . . . , r} to each vertex and each edge, moreover, for any color i all vertices of color i induce a subgraph with property P, all edges of color i induce a subgraph with property Q and vertices and incident edges have been assigned disjoint sets of...

Fractional (P,Q)-Total List Colorings of Graphs

Arnfried Kemnitz, Peter Mihók, Margit Voigt (2013)

Discussiones Mathematicae Graph Theory

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Let r, s ∈ N, r ≥ s, and P and Q be two additive and hereditary graph properties. A (P,Q)-total (r, s)-coloring of a graph G = (V,E) is a coloring of the vertices and edges of G by s-element subsets of Zr such that for each color i, 0 ≤ i ≤ r − 1, the vertices colored by subsets containing i induce a subgraph of G with property P, the edges colored by subsets containing i induce a subgraph of G with property Q, and color sets of incident vertices and edges are disjoint. The fractional...

Generalized Fractional Total Colorings of Complete Graph

Gabriela Karafová (2013)

Discussiones Mathematicae Graph Theory

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An additive and hereditary property of graphs is a class of simple graphs which is closed under unions, subgraphs and isomorphism. Let P and Q be two additive and hereditary graph properties and let r, s be integers such that r ≥ s Then an [...] fractional (P,Q)-total coloring of a finite graph G = (V,E) is a mapping f, which assigns an s-element subset of the set {1, 2, . . . , r} to each vertex and each edge, moreover, for any color i all vertices of color i induce a subgraph of property...

Fractional Q-Edge-Coloring of Graphs

Július Czap, Peter Mihók (2013)

Discussiones Mathematicae Graph Theory

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An additive hereditary property of graphs is a class of simple graphs which is closed under unions, subgraphs and isomorphism. Let [...] be an additive hereditary property of graphs. A [...] -edge-coloring of a simple graph is an edge coloring in which the edges colored with the same color induce a subgraph of property [...] . In this paper we present some results on fractional [...] -edge-colorings. We determine the fractional [...] -edge chromatic number for matroidal properties of...

The non-crossing graph.

Linial, Nathan, Saks, Michael, Statter, David (2006)

The Electronic Journal of Combinatorics [electronic only]

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The chromatic number of the product of two graphs is at least half the minimum of the fractional chromatic numbers of the factors

Claude Tardif (2001)

Commentationes Mathematicae Universitatis Carolinae

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One consequence of Hedetniemi’s conjecture on the chromatic number of the product of graphs is that the bound $χ (G \times H) \geq min {χ_{f} (G), χ_{f} (H)}$ should always hold. We prove that $χ (G \times H) \geq \frac{1}{2} min {χ_{f} (G), χ_{f} (H)}$ .

The set chromatic number of a graph

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

Discussiones Mathematicae Graph Theory

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For a nontrivial connected graph G, let c: V(G)→ 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) ≠ 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 χₛ(G) of G. The set chromatic numbers of some well-known classes of graphs...

Fractional biclique covers and partitions of graphs.

Watts, Valerie L. (2006)

The Electronic Journal of Combinatorics [electronic only]

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Bounds for the b-Chromatic Number of Subgraphs and Edge-Deleted Subgraphs

P. Francis, S. Francis Raj (2016)

Discussiones Mathematicae Graph Theory

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A b-coloring of a graph G with k colors is a proper coloring of G using k colors in which each color class contains a color dominating vertex, that is, a vertex which has a neighbor in each of the other color classes. The largest positive integer k for which G has a b-coloring using k colors is the b-chromatic number b(G) of G. In this paper, we obtain bounds for the b- chromatic number of induced subgraphs in terms of the b-chromatic number of the original graph. This turns out to be...

Coloring with no 2-colored $P_{4}$ 's.

Albertson, Michael O., Chappell, Glenn G., Kierstead, H.A., Kündgen, André, Ramamurthi, Radhika (2004)

The Electronic Journal of Combinatorics [electronic only]

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A Tight Bound on the Set Chromatic Number

Jean-Sébastien Sereni, Zelealem B. Yilma (2013)

Discussiones Mathematicae Graph Theory

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We provide a tight bound on the set chromatic number of a graph in terms of its chromatic number. Namely, for all graphs G, we show that χs(G) > ⌈log2 χ(G)⌉ + 1, where χs(G) and χ(G) are the set chromatic number and the chromatic number of G, respectively. This answers in the affirmative a conjecture of Gera, Okamoto, Rasmussen and Zhang.