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 Convexity Lemma and Expansion Procedures for Bipartite Graphs
✍ Scribed by W. Imrich; S. Klavžar
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 148 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0195-6698
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✦ Synopsis
A hierarchy of classes of graphs is proposed which includes hypercubes, acyclic cubical complexes, median graphs, almost-median graphs, semi-median graphs and partial cubes. Structural properties of these classes are derived and used for the characterization of these classes by expansion procedures, for a characterization of semi-median graphs by metrically defined relations on the edge set of a graph and for a characterization of median graphs by forbidden subgraphs. Moreover, a convexity lemma is proved and used to derive a simple algorithm of complexity O(mn) for recognizing median graphs.
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