REFERENCES
[1] N. Bourbaki, El´ements de Math´ematique. Topologie G´en´erale. Chapitres 5 `a 10 ´ , Hermann,
Paris, 1974.
[2] F. E. Browder, Fixed point theory and nonlinear problems, Bull. Amer. Math. Soc. (N.S.) 9
(1983), 1–39.
[3] I. Campa and M. Degiovanni, Subdifferential calculus and nonsmooth critical point theory,
SIAM J. Optim. 10 (2000), 1020–1048.
[4] K.-C. Chang, Infinite-dimensional Morse Theory and Multiple Solution Problems, Progress in
Nonlinear Differential Equations and their Applications, 6, Birkh¨auser Boston Inc., Boston,
MA, 1993.
[5] S. Cingolani and G. Vannella, Critical groups computations on a class of Sobolev Banach spaces
via Morse index, Ann. Inst. H. Poincar´e Anal. Non Lin´eaire 20 (2003), 271–292.
[6] S. Cingolani and G. Vannella, Marino-Prodi perturbation type results and Morse indices of
minimax critical points for a class of functionals in Banach spaces, Ann. Mat. Pura Appl. (4)
186 (2007), 157–185.
[7] J.-N. Corvellec, Morse theory for continuous functionals, J. Math. Anal. Appl. 196 (1995),
1050–1072.
[8] J.-N. Corvellec, On the second deformation lemma, Topol. Methods Nonlinear Anal. 17 (2001),
55–66.
[9] J.-N. Corvellec and A. Hantoute, Homotopical stability of isolated critical points of continuous
functionals, in: Calculus of Variations, Nonsmooth Analysis and Related Topics, (Ed.:
Degiovanni and Ioffe), Set-Valued Anal. 10 (2002), 143–164.
[10] E. De Giorgi, A. Marino, and M. Tosques, Problemi di evoluzione in spazi metrici e curve di
massima pendenza, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 68 (1980),
180–187.
[11] M. Degiovanni and M. Marzocchi, A critical point theory for nonsmooth functionals, Ann. Mat.
Pura Appl. (4) 167 (1994), 73–100.
[12] M. Degiovanni, M. Marzocchi, and V. D. R˘adulescu, Multiple solutions of hemivariational
inequalities with area-type term, Calc. Var. Partial Differential Equations 10 (2000), 355–387.
[13] M. Degiovanni and F. Schuricht, Buckling of nonlinearly elastic rods in the presence of obstacles
treated by nonsmooth critical point theory, Math. Ann. 311 (1998), 675–728.
[14] J. Dugundji and A. Granas, Fixed Point Theory, Springer Monographs in Mathematics,
Springer-Verlag, New York, 2003.
[15] S.-T. Hu, Theory of Retracts, Wayne State University Press, Detroit, 1965.
[16] A. Ioffe and E. Schwartzman, Metric critical point theory. I. Morse regularity and homotopic
stability of a minimum, J. Math. Pures Appl. (9) 75 (1996), 125–153.
[17] G. Katriel, Mountain pass theorems and global homeomorphism theorems, Ann. Inst. H.
Poincar´e Anal. Non Lin´eaire 11 (1994), 189–209.
[18] C. Li, S. Li, and J. Liu, Splitting theorem, Poincar´e-Hopf theorem and jumping nonlinear
problems, J. Funct. Anal. 221 (2005), 439–455.
[19] J. Mawhin and M. Willem, Critical Point Theory and Hamiltonian Systems, Applied Mathematical
Sciences, 74, Springer-Verlag, New York, 1989.
[20] R. S. Palais, Homotopy theory of infinite dimensional manifolds, Topology 5 (1966), 1–16.
[21] E. H. Spanier, Algebraic Topology, McGraw-Hill Book Co., New York, 1966.
[22] A. J. Tromba, A general approach to Morse theory, J. Differential Geometry 12 (1977), 47–85.
[23] K. Uhlenbeck, Morse theory on Banach manifolds, J. Functional Analysis 10 (1972), 430–445.
[24] J. E. West, Mapping Hilbert cube manifolds to ANR’s: a solution of a conjecture of Borsuk,
Ann. Math. (2) 106 (1977), 1–18.
[25] J. H. C. Whitehead, Combinatorial homotopy. I, Bull. Amer. Math. Soc. 55 (1949), 213–245.