On the diameter of i-center in a graph without long induced paths

  • Authors:
  • Jinquan Dong

  • Affiliations:
  • Departent of Mathematics, Northern Jiaotong University, Beijing, 100044, P.R. China

  • Venue:
  • Journal of Graph Theory
  • Year:
  • 1999

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Abstract

A graph G is said to be Pt-free if it does not contain an induced path on t vertices. The i-center Ci(G) of a connected graph G is the set of vertices whose distance from any vertex in G is at most i. Denote by I(t) the set of natural numbers i, ⌊t-2⌋ ≤ i ≤ t - 2, with the property that, in every connected Pt-free graph G, the i-center Ci(G) of G induces a connected subgraph of G. In this article, the sharp upper bound on the diameter of G[Ci(G)] is established for every i ∈ I(t). The sharp lower bound on I(t) is obtained consequently. © 1999 John Wiley & Sons, Inc. J Graph Theory 30: 235–241, 1999