ABSTRACT. An infinite system of ordinary differential equations for ~,/~, and for averages of a set of operators is derived for quantum-mechanical problems with a (K x K) matrix Hamiltonian 74(~,/~), z E R N 9 The set of operators is chosen to be basis in the space MatKC @ UOSYN) , where U(WN) is the universal enveloping algebra of the Heisenberg-Weyl algebra FVN, generated by the time-dependent operators ], ~ -e(t) 9 I, and /~ -/~(t) 9 ], where ] is the identity operator and ~ and /~ are the averages of the position and momentum operators. The system in question can be written in Hamiltonian form; the corresponding Poisson bracket is degenerate and is equal to the sum of the standard bracket on R ~N with respect to the variables (~',/~) and the generalized Dirac bracket with respect to the other variables. The possibility of obtaining finite-dimensional approximations to the infinite-dimensional system in the semiclassical limit h ---, 0 is investigated.