English

$\chi_D(G)$, $|Aut(G)|$, and a variant of the Motion Lemma

Combinatorics 2015-05-14 v1

Abstract

The \textit{Distinguishing Chromatic Number} of a graph GG, denoted χD(G)\chi_D(G), was first defined in \cite{collins} as the minimum number of colors needed to properly color GG such that no non-trivial automorphism ϕ\phi of the graph GG fixes each color class of GG. In this paper, 1. We prove a lemma that may be considered a variant of the Motion lemma of \cite{RS} and use this to give examples of several families of graphs which satisfy χD(G)=χ(G)+1\chi_D(G)=\chi(G)+1. 2.We give an example of families of graphs that admit large automorphism groups in which every proper coloring is distinguishing. We also describe families of graphs with (relatively) very small automorphism groups which satisfy χD(G)=χ(G)+1\chi_D(G)=\chi(G)+1, for arbitrarily large values of χ(G)\chi(G). 3. We describe non-trivial families of bipartite graphs that satisfy χD(G)>r\chi_D(G)>r for any positive integer rr.

Keywords

Cite

@article{arxiv.1505.03396,
  title  = {$\chi_D(G)$, $|Aut(G)|$, and a variant of the Motion Lemma},
  author = {Niranjan Balachandran and Sajith Padinhatteeri},
  journal= {arXiv preprint arXiv:1505.03396},
  year   = {2015}
}

Comments

20 pages, 2 figures. arXiv admin note: text overlap with arXiv:1406.5358