Degree sum conditions for hamiltonian index

Abstract

In this note, we show a sharp lower bound of \(\min \left\{{\sum\nolimits_{i = 1}^k {{d_G}({u_i}):{u_1}{u_2} \ldots {u_k}}} \right.\) is a path of (2-)connected G on its order such that (k-1)-iterated line graphs L^k−1(G) are hamiltonian.