A general model is proposed for constrained dynamical systems on a symplect
ic manifold which covers, among others, the description of Lagrangian and H
amiltonian systems with nonholonomic constraints and the canonical descript
ion of mechanical systems with a singular Lagrangian. The reduction propert
ies of these systems in the presence of symmetry are investigated within th
is general framework. (C) 1999 American Institute of Physics. [S0022-2488(9
9)00902-0].