On the size of identifying codes in triangle-free graphs

  • Authors:
  • Florent Foucaud;Ralf Klasing;Adrian Kosowski;André Raspaud

  • Affiliations:
  • University Bordeaux, LaBRI, UMR5800, F-33400 Talence, France and CNRS, LaBRI, UMR5800, F-33400 Talence, France;University Bordeaux, LaBRI, UMR5800, F-33400 Talence, France and CNRS, LaBRI, UMR5800, F-33400 Talence, France;University Bordeaux, LaBRI, UMR5800, F-33400 Talence, France and CNRS, LaBRI, UMR5800, F-33400 Talence, France and INRIA, F-33400 Talence, France and Department of Algorithms and System Modeling, ...;University Bordeaux, LaBRI, UMR5800, F-33400 Talence, France and CNRS, LaBRI, UMR5800, F-33400 Talence, France

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

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Abstract

In an undirected graph G, a subset C@?V(G) such that C is a dominating set of G, and each vertex in V(G) is dominated by a distinct subset of vertices from C, is called an identifying code of G. The concept of identifying codes was introduced by Karpovsky, Chakrabarty and Levitin in 1998. For a given identifiable graph G, let @c^I^D(G) be the minimum cardinality of an identifying code in G. In this paper, we show that for any connected identifiable triangle-free graph G on n vertices having maximum degree @D=3, @c^I^D(G)@?n-n@D+o(@D). This bound is asymptotically tight up to constants due to various classes of graphs including (@D-1)-ary trees, which are known to have their minimum identifying code of size n-n@D-1+o(1). We also provide improved bounds for restricted subfamilies of triangle-free graphs, and conjecture that there exists some constant c such that the bound @c^I^D(G)@?n-n@D+c holds for any nontrivial connected identifiable graph G.