“…As a degenerated case of the algebro-geometric solution, the elliptic function solution and multi-soliton solution may be worked out [1,22,25]. The inverse spectral theory has been extended to the whole (1+1) dimensional integrable hierarchy by Gesztesy and Holden, such as the AKNS hierarchy, the Camassa-Holm hierarchy, and so on [9,10,11,12]. In recent years, Fan and his co-authors [15,16,17,18,29,30,31] investigated the Ruijsenaars-Toda Hierarchy, the Degasperis-Procesi hierarchy, derivative Burgers hierarchy, etc., and obtained their algebro-geometric solutions.…”