Forbidden Subgraph Colorings and the Oriented Chromatic Number

: We present an improved upper bound of O(d1+ 1 m−1 ) for the (2, F)-subgraph chromatic number χ2,F (G) of any graph G of maximum degree d. Here, m denotes the minimum number of edges in any member of F. This bound is tight up to a (log d)1/(m−1) multiplicative factor and improves the previous bound presented in [1]. We also obtain a relationship connecting the oriented chromatic number χo(G) of graphs and the (j, F)-subgraph chromatic numbers χj,F (G) introduced and studied in [1]. In particular, we relate oriented chromatic number and the (2, r)-treewidth chromatic number and show that χo(G) ≤ k ((r + 1)2r )k−1 for any graph G having (2, r)-treewidth chromatic number at most k. The latter parameter is the least number of colors in any proper vertex coloring which is such that the subgraph induced by the union of any two color classes has treewidth at most r. We also generalize a result of Alon, et. al. [2] on acyclic chromatic number of graphs on surfaces to (2, F)-subgra...

• Type: Conference
• Year: 2009
• Where: IWOCA
• Authors: N. R. Aravind, C. R. Subramanian
• Keywords: Algorithms, Chromatic Number, F)-subgraph Chromatic Numbers, IWOCA 2009, Oriented Chromatic Number