  We discuss equivalent representations of the collective/bosonic Hamiltonian
in the form of Taylor expansion over collective coordinate and momentum.
Different expansions are equivalent if they are related by a transformation of
collective variables. The independent parameters in the collective Hamiltonian
are identified, which are much less in number than it appears. In this sense,
the microscopic generalized density matrix method fixes the collective
Hamiltonian completely, which seems to solve the old problem of microscopic
calculation of the collective Hamiltonian.
