  An abstract linking result for Cerami sequences is proved without the Cerami
condition. It is applied directly in order to prove the existence of critical
points for a class of indefinite problems in infinite dimensional Hilbert
Spaces. The main applications are given to Hamiltonian systems and Schrodinger
equations. Here spectral properties of the operators are exploited and
hypotheses of monotonicity on the nonlinearities are discarded.
