Long cycles in triangle-free graphs with prescribed independence number and connectivity

  • Authors:
  • Hikoe Enomoto;Atsushi Kaneko;Akira Saito;Bing Wei

  • Affiliations:
  • Department of Mathematics, Keio University, Hiyoshi 3-14-1 Kohoku-Ku, Yokohama 223-8522, Japan;Department of Electronic Engineering, Kogakuin University, Nishi-Shinjuku 1-24-2, Shinjuku-Ku, Tokyo 163-8677, Japan;Department of Applied Mathematics, Nihon University, Sakurajosui 3-25-40, Setagaya-Ku, Tokyo 156-8550, Japan;Institute of Systems Science, Academia Sinica, Beijing 100080, China

  • Venue:
  • Journal of Combinatorial Theory Series B
  • Year:
  • 2004

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Abstract

The Chvátal-Erdös theorem says that a 2-connected graph with α(G)≤κ(G) is hamiltonian. We extend this theorem for triangle-free graphs. We prove that if G is a 2-connected triangle-free graph of order n with α(G)≤2κ(G) - 2, then every longest cycle in G is dominating, and G has a cycle of length at least min{n - α(G) + κ(G), n}.