L(2,1)-labeling of direct product of paths and cycles

  • Authors:
  • Pranava K. Jha;Sandi Klavar;Aleksander Vesel

  • Affiliations:
  • Department of Computer Science, St. Cloud State University, St. Cloud, MN 56301, USA;Department of Mathematics and Computer Science, PeF, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia;Department of Mathematics and Computer Science, PeF, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia

  • Venue:
  • Discrete Applied Mathematics - Structural decompositions, width parameters, and graph labelings (DAS 5)
  • Year:
  • 2005

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Abstract

An L(2,1)-labeling of a graph G is an assignment of labels from {0,1,...,@l} to the vertices of G such that vertices at distance two get different labels and adjacent vertices get labels that are at least two apart. The @l-number @l(G) of G is the minimum value @l such that G admits an L(2,1)-labeling. Let GxH denote the direct product of G and H. We compute the @l-numbers for each of C"7"ixC"7"j, C"1"1"ixC"1"1"jxC"1"1"k, P"4xC"m, and P"5xC"m. We also show that for n=6 and m=7, @l(P"nxC"m)=6 if and only if m=7k, k=1. The results are partially obtained by a computer search.