It was proved by Hell and Zhu that, if G is a series-parallel graph of girth at least 2 (3k -1)/2 , then Ο c (G) β€ 4k/(2k -1). In this article, we prove that the girth requirement is sharp, i.e., for any k β₯ 2, there is a series-parallel graph G of girth 2 (3k -1)/2 -1 such that Ο c (G) > 4k/(2k -1)
List edge chromatic number of graphs with large girth
β Scribed by A.V. Kostochka
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 785 KB
- Volume
- 101
- Category
- Article
- ISSN
- 0012-365X
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β¦ Synopsis
Kostochka, A.V., List edge chromatic number of graphs with large girth, Discrete Mathematics 101 (1992) 189-201. It is shown that the list edge chromatic number of any graph with maximal degree A and girth at least 8A(ln A + 1.1) is equal to A + 1 or to A. Conjecture 1. The list edge chromatic number lee of any graph G does not exceed A(G) + 1. Conjecture 2. The list edge chromatic number of any multigraph is equal to its edge chromatic number (i.e. chromatic index). The notion of list colouring was also independently introduced by Erdiis, Rubin and Taylor [4], and Conjecture 2-by Albertson and Tucker. Conjecture 1 implies that Total Colouring Conjecture is 'almost true'. Conjectures 1 and 2 are proved only for very small classes of graphs: snarks, trees, cycles (cf. [3]), planar graphs with maximal degree at least 9 [2]. As far as we know the best general bounds for ZeX(G) and Q(G) are the following.
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