Reverse-order lower and upper functions for periodic problems of second-order singular difference equations
Summary: We present sufficient conditions ensuring the lower and upper functions on the reversed-order for the periodic difference equations. This enables us to obtain the existence of positive periodic solutions of the second-order difference equation \(\Delta^2 u(t-1)=g(t)/u^\mu(t)-h(t)/u^\lambda(t)+f(t)\), \(t\in\mathbb Z\) where \(g,h:\mathbb Z\to[0,\infty)\), and \(f:\mathbb Z\to\mathbb R\) are \(T\)-periodic functions, \(\lambda,\mu >0\).
scientific article; zbMATH DE number 6306101