The nonlinearization approach is generalized to the case of the Neumann con
straint associated with a discrete 3 x 3 matrix eigenvalue problem. A new s
ymplectic map of the Neumann type is obtained by nonlinearization of the di
screte eigenvalue problem and its adjoint one. A scheme for generating the
involutive system of conserved integrals of the symplectic map is proposed,
by which the symplectic map of the Neumann type is further proved to compl
etely integrable. As an application. the calculation of solutions for the h
ierarchy of lattice soliton equations connected to the discrete eigenvalue
problem is reduced to the solutions of a system of ordinary differential eq
uations plus a simple iterative process of the symplectic map of the Neuman
n type.