We study weakly coupled superlinear systems with different boundary conditions. The boundary conditions that we consider are the Sturm-Liouville and the three-point boundary conditions. We first prove a continuation theorem based on coincidence degree and explain how to compute the degree for some simple scalar differential equations. Then we apply those results to prove the existence of infinitely many solutions to the weakly coupled system.
"Infinitely many solutions of weakly coupled superlinear systems." Adv. Differential Equations 2 (5) 753 - 778, 1997.