Existence of Four Solutions of Some Nonlinear Hamiltonian System
1 Department of Mathematics, Kunsan National University, Kunsan 573-701, South Korea
2 Department of Mathematics Education, Inha University, Incheon 402-751, South Korea
Boundary Value Problems 2008, 2008:293987 doi:10.1155/BVP/2008/293987Published: 14 January 2008
We show the existence of four -periodic solutions of the nonlinear Hamiltonian system with some conditions. We prove this problem by investigating the geometry of the sublevels of the functional and two pairs of sphere-torus variational linking inequalities of the functional and applying the critical point theory induced from the limit relative category.