Hamiltonian cycles and Hamiltonian paths in $2k$-connected, $1$-tough and $(P_3\cup k{P}_1)$-free graphs

Abstract

A graph $G$ is called Hamiltonian if it possesses a Hamiltonian cycle; and $G$ is called Hamiltonian-connected if it contains a Hamiltonian path between any two distinct vertices. The toughness of a non-complete graph is the minimum ratio of $|S|$ to the number of components of $G-S$ for any cutset $S$. For a given graph $H$, a graph $G$ is called $H$-free if $G$ does not contain $H$ as an induced subgraph. In this paper, for an integer $k\ge 2$, we prove that every $2k$-connected, $1$-tough and $(P_3\cup k{P}_1)$-free graph is Hamiltonian and every $(2k+1)$-connected $(P_3\cup k{P}_1)$-free graph with toughness greater than $1$ is Hamiltonian-connected.