文摘
It is shown by Luo and Zhao (J Graph Theory 73:469–482, 2013) that an overfull \(\Delta \)-critical graph with n vertices that satisfies \(\Delta \ge \frac{n}{2}\) is Hamiltonian. If Hilton’s overfull subgraph conjecture (Chetwynd and Hilton 100:303–317, 1986) was proved to be true, then the above result could be said that any \(\Delta \)-critical graph with n vertices that satisfies \(\Delta \ge \frac{n}{2}\) is Hamiltonian. Since the overfull subgraph conjecture is still open, the natural question is how to directly prove a \(\Delta \)-critical graph with n vertices that satisfies \(\Delta \ge \frac{n}{2}\) is Hamiltonian. Luo and Zhao (J Graph Theory 73:469–482, 2013) show that a \(\Delta \)-critical graph with n vertices that satisfies \(\Delta \ge \frac{6n}{7}\) is Hamiltonian. In this paper, by developing new lemmas for critical graphs, we show that if G is a \(\Delta \)-critical graph with n vertices satisfying \(\Delta \ge \frac{4n}{5}\), then G is Hamiltonian.