Selected Aspects of Soliton Theory. Constant boundary conditions

Brief review of the methods for solving the multicomponent nonlinear Schrodinger (MNLS) equations and analysis of their Hamiltonian structures is given. Main attention is paid to the MNLS related to the C.II- and D.III-types symmetric spaces with nonvanishing (constant) boundary conditions. The spectral properties of their Lax operators are described. The derivation of the trace identities is outlined. The involutivity of their integrals of motion is proved using the method of the classical R-matrix.