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On the cost chromatic number of outerplanar, planar, and line graphs

John Mitchem, Patrick Morriss, Edward Schmeichel (1997)

Discussiones Mathematicae Graph Theory

We consider vertex colorings of graphs in which each color has an associated cost which is incurred each time the color is assigned to a vertex. The cost of the coloring is the sum of the costs incurred at each vertex. The cost chromatic number of a graph with respect to a cost set is the minimum number of colors necessary to produce a minimum cost coloring of the graph. We show that the cost chromatic number of maximal outerplanar and maximal planar graphs can be arbitrarily large and construct...

On the Crossing Numbers of Cartesian Products of Stars and Graphs of Order Six

Marián Klešč, Štefan Schrötter (2013)

Discussiones Mathematicae Graph Theory

The crossing number cr(G) of a graph G is the minimal number of crossings over all drawings of G in the plane. According to their special structure, the class of Cartesian products of two graphs is one of few graph classes for which some exact values of crossing numbers were obtained. The crossing numbers of Cartesian products of paths, cycles or stars with all graphs of order at most four are known. Moreover, except of six graphs, the crossing numbers of Cartesian products G⃞K1,n for all other...

On the Crossing Numbers of Cartesian Products of Wheels and Trees

Marián Klešč, Jana Petrillová, Matúš Valo (2017)

Discussiones Mathematicae Graph Theory

Bokal developed an innovative method for finding the crossing numbers of Cartesian product of two arbitrarily large graphs. In this article, the crossing number of the join product of stars and cycles are given. Afterwards, using Bokal’s zip product operation, the crossing numbers of the Cartesian products of the wheel Wn and all trees T with maximum degree at most five are established.

On the crossing numbers of G □ Cₙ for graphs G on six vertices

Emília Draženská, Marián Klešč (2011)

Discussiones Mathematicae Graph Theory

The crossing numbers of Cartesian products of paths, cycles or stars with all graphs of order at most four are known. The crossing numbers of G☐Cₙ for some graphs G on five and six vertices and the cycle Cₙ are also given. In this paper, we extend these results by determining crossing numbers of Cartesian products G☐Cₙ for some connected graphs G of order six with six and seven edges. In addition, we collect known results concerning crossing numbers of G☐Cₙ for graphs G on six vertices.

On the Decompositions of Complete Graphs into Cycles and Stars on the Same Number of Edges

Atif A. Abueida, Chester Lian (2014)

Discussiones Mathematicae Graph Theory

Let Cm and Sm denote a cycle and a star on m edges, respectively. We investigate the decomposition of the complete graphs, Kn, into cycles and stars on the same number of edges. We give an algorithm that determines values of n, for a given value of m, where Kn is {Cm, Sm}-decomposable. We show that the obvious necessary condition is sufficient for such decompositions to exist for different values of m.

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