Claw-Free Graphs and Separating Independent Sets On 2-Factors

Document Type

Article

Publication Date

3-2012

Publication Title

Journal of Graph Theory

DOI

10.1002/jgt.20579

ISSN

1097-0118

Abstract

In this article, we prove that a line graph with minimum degree δ≥7 has a spanning subgraph in which every component is a clique of order at least three. This implies that if G is a line graph with δ≥7, then for any independent set S there is a 2-factor of G such that each cycle contains at most one vertex of S. This supports the conjecture that δ≥5 is sufficient to imply the existence of such a 2-factor in the larger class of claw-free graphs.

It is also shown that if G is a claw-free graph of order n and independence number α with δ≥2n/α−2 and n≥3α3/2, then for any maximum independent set S, G has a 2-factor with α cycles such that each cycle contains one vertex of S. This is in support of a conjecture that δ≥n/α≥5 is sufficient to imply the existence of a 2-factor with α cycles, each containing one vertex of a maximum independent set.

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