b-chromatic number of cacti
نویسندگان
چکیده
منابع مشابه
B-chromatic Number of Cacti
A b-colouring of a graph G is a proper colouring of G such that each colour contains a vertex that is adjacent to all other colours and the b-chromatic number χb(G) is the maximum number of colours used in a b-colouring of G. If m(G) is the largest integer k such that G has at least k vertices with degree at least k − 1, then we know that χb(G) ≤ m(G). Irving and Manlove [1] prove that, if T is...
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Computing the chromatic number of a graph is an NP-hard problem. For random graphs and some other classes of graphs, estimators of the expected chromatic number have been well studied. In this paper, a new 0–1 integer programming formulation for the graph coloring problem is presented. The proposed new formulation is used to develop a method that generates graphs of known chromatic number by us...
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The b-chromatic number of a graph G is the largest integer k such that G admits a proper k-coloring in which every color class contains at least one vertex adjacent to some vertex in all the other color classes. It is proved that with four exceptions, the b-chromatic number of cubic graphs is 4. The exceptions are the Petersen graph, K3,3, the prism over K3, and one more sporadic example on 10 ...
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The achromatic number ψ(G) of a graph G = (V,E) is the maximum k such that V has a partition V1, V2, . . . , Vk into independent sets, the union of no pair of which is independent. Here we show that ψ(G) can be viewed as the maximum over all minimal elements of a partial order defined on the set of all colourings of G. We introduce a natural refinement of this partial order, giving rise to a ne...
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ژورنال
عنوان ژورنال: Electronic Notes in Discrete Mathematics
سال: 2009
ISSN: 1571-0653
DOI: 10.1016/j.endm.2009.11.046