A new Morse theory and strong resonance problems
In this interesting paper the author presents a Morse type theory for functions \(f\) which do not satisfy the (PS) condition at some isolated values. He also considers some multiplicity results for strong resonance problems in connection to multiple resonant energy levels. I want to mention that such a theory was first introduced by \textit{T. Bartsch} and the author [Nonlinear Anal., Theory Methods Appl. 28, No. 3, 419--441 (1997; Zbl 0872.58018)] for the local behavior of functions \(f\) near infinity.
scientific article; zbMATH DE number 2052552