It is proved that there is a function f: N Q N such that the following holds. Let G be a graph embedded in a surface of Euler genus g with all faces of even size and with edge-width \ f(g). Then (i) If every contractible 4-cycle of G is facial and there is a face of size > 4, then G is 3-colorable.
On equitable coloring of bipartite graphs
β Scribed by Ko-Wei Lih; Pou-Lin Wu
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 285 KB
- Volume
- 151
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
If the vertices of a graph G are partitioned into k classes V~, I/2 ..... Vk such that each V~ is an independent set and I1V~I-IV~[I ~< 1 for all i#j, then G is said to be equitably colored with k colors. The smallest integer n for which G can be equitably colored with n colors is called the equitable chromatic number xc(G) of G. The Equitable Coloring Conjecture asserts that zc(G) ~ A(G) for all connected graphs G except the complete graphs and the odd cycles. We show that this conjecture is true for any connected bipartite graph G(X, Y). Furthermore, if IXI = m/> n = I YI and the number of edges is less than Lm/(n + 1)J(m --n) + 2m, then we can establish an improved bound Xo (G) ~< Fm/(n + 1)-] + 1.
π SIMILAR VOLUMES
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