Stability of a Class of Nonlinear Difference Equations

In this paper using KAM theory we investigate the stability nature of the zero equilibrium of the system of two nonlinear difference equations xnq1sa1xnqb1ynqf c1xnqc2yn. 5, ns0, 1, . . . , ynq1sa2xnqb2ynqf c1xnqc2yn. where ai, bi, ci, is1, 2, are real constants and f : RªR is a C` function.