| Conditions are given for the existence of three positive solutions to the discrete second order conjugate boundary value problem (BVP), the discrete (n-1,1) focal BVP, the continuous (n-1,1) focal BVP, and the discrete (n-2,2) focal BVP applying the Leggett-Williams Fixed Point Theorem. Existence of three positive solutions to the above discrete BVP's applying other fixed point theorems is included. The last chapter is devoted to giving conditions for a summation equation, which could be used to model infectious diseases, to have a nontrivial periodic solution. |
