“…Due to its wide application in many fields such as science, economics, neural networks, ecology and cybernetics, the theory of nonlinear difference equations has been widely studied since the 1970s; see, for example, [1,6,21,22]. At the same time, boundary value problems (BVPs) of difference equations have received much attention from many authors; see [2-5, 7-13, 15, 18-20, 25-31] and the references therein.…”