Positive periodic solutions for nonlinear difference equations with periodic coefficients (Q1284516)

The authors consider the following boundary value problem \[ -\Delta [p(n-1)\Delta y(n-1)]+q(n) y(n)=f(n,y(n)), \quad n=1,2,\dots,N, \] \[ y(0)=y(N),\qquad p(0)\Delta y(0)=p(N)\Delta y(N). \] Using a fixed point theorem in cones, existence of one as well as two solutions is established for the boundary value problem. The authors also consider the boundary value problem with a parameter. Finally, existence of positive periodic solutions on the whole discrete axis is established when the coefficients of the boundary value problem are periodic.