Type numbers of critical points for nonsmooth functionals (Q1810241)

The author develops the rigorous variant of Morse theory for Lipschitz functionals \(f\) in separable reflexive Banach spaces; \(\partial f\) belongs to set-valued analog of the class \((S)_+\), it is a substitute for the Palais-Smale condition. For the collection: Lyusternik-Schnirelman theory for Lipschitz functionals see \textit{K. C.~Chang} [J. Math. Anal. Appl. 80, 102-129 (1981; Zbl 0487.49027)]; \textit{W.~Krawcewicz} and \textit{W.~Marzantowicz} [Rocky Mt. J. Math. 20, 1041-1049 (1990; Zbl 0728.58005)]; \textit{V. D. Rǎdulescu} [Proc. Japan Acad., Ser A 71, 164-167 (1995; Zbl 0853.58031)].