The total chromatic number χ T (G) of graph G is the least number of colors assigned to V (G) ∪ E(G) such that no adjacent or incident elements receive the same color. In this article, we give a sufficient condition for a bipartite graph G to have χ T (G) = ∆(G) + 1.
A sufficient condition for planar graphs to be acyclically 5-choosable
✍ Scribed by Min Chen; André Raspaud
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 216 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
A proper vertex coloring of a graph G = (V, E) is acyclic if G contains no bicolored cycle. Given a list assignment L = {L(v)|v∈V} of G, we say G is acyclically L‐list colorable if there exists a proper acyclic coloring π of G such that π(v)∈L(v) for all v∈V. If G is acyclically L‐list colorable for any list assignment with |L(v)|≥k for all v∈V, then G is acyclically k‐choosable. In this article we prove that every planar graph without 4‐cycles and without intersecting triangles is acyclically 5‐choosable. This improves the result in [M. Chen and W. Wang, Discrete Math 308 (2008), 6216–6225], which says that every planar graph without 4‐cycles and without two triangles at distance less than 3 is acyclically 5‐choosable. © 2011 Wiley Periodicals, Inc. J Graph Theory
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