Normal forms and the multiple-times expansion method for finite-dimensional integrable Hamiltonian systems

The authors apply the method of multiple-times expansion to finite-dimensional integrable Hamiltonian systems of polynomial type in order to determine integrable Hamiltonian systems and to derive new integrable systems from previously known ones. Recursion operators for the derived integrable systems are obtained. Normal forms for finite-dimensional integrable Hamiltonian systems are also constructed. It is demonstrated that the Hamiltonians found by the multiple-times expansion method are indeed the normal form expansions.