Convergence of solutions for a class of neutral difference equations

Consider the neutral difference equation (xn−cxn−k)=f(n, xn, xn−k), where k is a positive integer, 0 < c < 1, denotes the backward difference operator yn = yn − yn−1, f : N × R2 → R is continuous and decreasing with respect to the second argument. We give the results that solutions of the equation convergent to constants.