Article
Keywords:
fixed point; Hilbert space; weak topology; discontinouous operator
Summary:
We construct a class of discontinuous operators in infinite-dimensional separable Hilbert spaces, answering a natural question which arises in comparing a fixed point theorem of Altman and Shinbrot ([1], [4]) with its improvement obtained by Ricceri ([2], [3]).
References:
[1] Altman M.:
A fixed point theorem in Hilbert space. Bull. Acad. Polon. Sci. Sér. Sci. Math. Astronom. Phys. 5 (1957), 19-22.
MR 0087064 |
Zbl 0077.31902
[2] Ricceri B.:
Un théorème d'existence pour les inéquations variationnelles. C.R. Acad. Sci. Paris, Série I 301 (1985), 885-888.
MR 0823146 |
Zbl 0606.49006
[3] Ricceri B.:
Existence theorems for nonlinear problems. Rend. Accad. Naz. Sci. XL 11 (1987), 77-99.
MR 0930860 |
Zbl 0643.47058