Two Positive Periodic Solutions of Delay Functional Difference System with Feedback Control

By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form △x(n) = -b(n)x(n) + f(n,x(n - τ1(n)),… ,x(n - τm(n)),u(n - δ(n))), △u(n) = -η(n)u(n) + a(n)x(n - σ(n)), n ∈ Z.