“…From then on, this conjecture has been confirmed only for k-connected graphs with k ≤ 4 (see [9,10,14]). Since this conjecture is still unsolved for general k-connected graphs for k ≥ 5, the follow-up research mainly focused on the study of constructing ISTs on specific interconnection networks, e.g., the construction of ISTs on some variations of hypercubes [3,20,29,30,37], torus networks [28], recursive circulant graphs [34,35], and special subclasses of Cayley networks [7,8,12,13,15,19,39]. In particular, special topics related to ISTs include the research on reducing the height of the ISTs [31,33,36] and parallel construction of ISTs [4-6, 32, 37, 38].…”