Displaying similar documents to “A class of tight circulant tournaments”

A lower bound for the packing chromatic number of the Cartesian product of cycles

Yolandé Jacobs, Elizabeth Jonck, Ernst Joubert (2013)

Open Mathematics

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Let G = (V, E) be a simple graph of order n and i be an integer with i ≥ 1. The set X i ⊆ V(G) is called an i-packing if each two distinct vertices in X i are more than i apart. A packing colouring of G is a partition X = {X 1, X 2, …, X k} of V(G) such that each colour class X i is an i-packing. The minimum order k of a packing colouring is called the packing chromatic number of G, denoted by χρ(G). In this paper we show, using a theoretical proof, that if q = 4t, for some integer t...

On rainbowness of semiregular polyhedra

Stanislav Jendroľ, Štefan Schrötter (2008)

Czechoslovak Mathematical Journal

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We introduce the rainbowness of a polyhedron as the minimum number k such that any colouring of vertices of the polyhedron using at least k colours involves a face all vertices of which have different colours. We determine the rainbowness of Platonic solids, prisms, antiprisms and ten Archimedean solids. For the remaining three Archimedean solids this parameter is estimated.