Periodic solutions of quasi-differential equations

[摘要] Existence principles and theorems are established for the nonlinear problemLu=f(t,u)whereLu=−(pu′)′+huis a quasi-differential operator andfis a Carathéodory function. We prove a maximum principle for the operatorLand then we show the validity of the upper and lower solution method as well as the monotone iterative technique.

[学科分类] 应用数学