ABSTRACT
This paper investigates multiple solutions for super-linear symmetric operator equations by optimization methods like index theory, Mountain pass theorem and mini-max methods. Applying the results to second order Hamiltonian systems with symmetry yields finite or infinitely many solutions.
Acknowledgments
The author thanks Professor Hong-Kun Xu for introducing her to the conference of fixed point theory and its applications. She also thank the anonymous referees for the quite valuable comments.
Disclosure statement
No potential conflict of interest was reported by the author(s).