A Liouville integrable Hamiltonian system associated with a generalized Kaup-Newell spectral problem

Starting from a generalized Kaup-Newell spectral problem involving an arbit rary function, we derive a hierarchy of nonlinear evolution equations, whic h is explicitly related to many important equations such as Kaup-Newell equ ation, Chen-Lee-Liu. equation, Gerdjikov-Ivanov equation, Burgers equation, modified Korteweg-de Vries equation and Sharma-Tasso-Olever equation. It i s also shown that the hierarchy is integrable in Lionville's sense and poss esses multi-Hamiltonian structure. (C) 2001 Elsevier Science B.V. All right s reserved.