The hamiltonian index of a graph $G$ is the smallest integer $k$ such that the $k$-th iterated line graph of $G$ is hamiltonian. We first show that, with one exceptional case, adding an edge to a graph cannot increase its hamiltonian index. We use this result to prove that neither the contraction of an $A_G(F)$-contractible subgraph $F$ of a graph $G$ nor the closure operation performed on $G$ (if $G$ is claw-free) affects the value of the hamiltonian index of a graph $G$.
|Place of Publication||Enschede|
|Publisher||University of Twente, Department of Applied Mathematics|
|Publication status||Published - 2002|
|Publisher||Department of Applied Mathematics, University of Twente|
Xiong, L., Ryjáček, Z., & Broersma, H. J. (2002). On stability of the Hamiltonian index under contractions and closures. (Memorandum; No. 1622). Enschede: University of Twente, Department of Applied Mathematics.