A note on periodic solutions of second order nonautonomous singular coupled systems (Q613821)

Summary: We establish the existence of periodic solutions of the second order nonautonomous singular coupled systems \[ x^{\prime\prime}+a_{1}(t)x=f_{1}(t,y(t))+e_{1}(t)\text{ for a.e. }t\in [0,T], \] \[ y''+a_{2}(t)y=f_{2}(t,x(t))+e_{2}(t)\text{ for a.e. }t\in [0,T]. \] The proof relies on Schauder's fixed point theorem.