Further results on hierarchical product of graphs

The hierarchical product of graphs was introduced very recently by L. Barriére et al. in [L. Barriére, F. Comellas, C. Dafló and M. A. Fiol, On the spectra of hypertrees, Linear Algebra Appl. 428 (2008) 1499–1510]. In this paper, some properties of the hierarchical product, as well as its extension under Szeged, revised Szeged and edge Szeged indices of graphs are studied.