SOLUTIONS AND POSITIVE SOLUTIONS TO SEMIPOSITONE DIRICHLET BVPS ON TIME SCALES

In this paper, we are concerned with the following Dirichlet boundary value problem on a time scale T ( −u ∆∆(t) = g(t, u(t)), t ∈ [0, T]T, u(0) = 0 = u(σ 2 (T)), where g : [0, T]T×[−σ(T)σ 2 (T)M, +∞) → [−M, +∞) is continuous and M > 0 is a constant, which implies that this problem is semipositone. For an arbitrary positive integer n, some existence results for n solutions and/or positive solutions are established by using the well-known Guo-Krasnosel’skii fixed point theorem. Our conditions imposed on g are local. An example is also included to illustrate the importance of the results obtained.