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On a three critical points theorem. (English) Zbl 0979.35040
The author consider a smooth functional depending on a real parameter λ. He obtains certain results on existence of an open interval of λ’s for which there exist at least three critical points. An application to a semilinear Dirichlet problem is mentioned.

MSC:
35J20Second order elliptic equations, variational methods
49J35Minimax problems (existence)
58E05Abstract critical point theory