Spectral radius and traceability of connected claw-free graphs

Abstract

Let $G$ be a connected claw-free graph on $n$ vertices and $\overline{G}$ be its complement graph. Let $\hat{I}¼(G)$ be the spectral radius of $G$. Denote by $N_{n-3,3}$ the graph consisting of $K_{n-3}$ and three disjoint pendent edges. In this note we prove that: (1) If $\hat{I}¼(G)\ge n-4$, then $G$ is traceable unless $G=N_{n-3,3}$. (2) If $\hat{I}¼(\overline{G})\le \hat{I}¼(\overline{N_{n-3,3}})$ and $n\ge 24$, then $G$ is traceable unless $G=N_{n-3,3}$. Our works are counterparts on claw-free graphs of previous theorems due to Lu et al., and Fiedler and Nikiforov, respectively.

12 pages,3 figures,to appear in FLOMAT