Another step towards proving a conjecture by Plummer and Toft
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Another step towards proving a conjecture by Plummer and Toft
A cyclic colouring of a graph G embedded in a surface is a vertex colouring of G in which any two distinct vertices sharing a face receive distinct colours. The cyclic chromatic number χc(G) of G is the smallest number of colours in a cyclic colouring of G. Plummer and Toft in 1987 conjectured that χc(G) ≤ ∆ ∗+2 for any 3-connected plane graph G with maximum face degree ∆∗. It is known that the...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2010
ISSN: 0012-365X
DOI: 10.1016/j.disc.2009.03.016