On the b-chromatic number of regular graphs without 4-cycle

  • Authors:
  • Saeed Shaebani

  • Affiliations:
  • -

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2012

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Abstract

The b-chromatic number of a graph G, denoted by @f(G), is the largest integer k for which G admits a proper coloring by k colors, such that each color class has a vertex that is adjacent to at least one vertex in each of the other color classes. We prove that, for each d-regular graph G which contains no 4-cycle, @f(G)=@?d+32@?; and besides, if G has a triangle, then @f(G)=@?d+42@?. Also, if G is a d-regular graph that contains no 4-cycle and diam(G)=6, then @f(G)=d+1. Finally, we show that, for any d-regular graph G which does not contain 4-cycle and has vertex connectivity less than or equal to d+12, @f(G)=d+1. Moreover, when the vertex connectivity is less than 3d-34, we introduce a lower bound for the b-chromatic number in terms of the vertex connectivity.