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Equilibrium problems with lower and upper bounds in topological spaces. (English) Zbl 1082.49007
Summary: Employing a fixed-point theorem due to X. P. Ding, J. Y. Park and I. H. Jung [Positivity 8, No. 4, 315–326 (2004; Zbl 1081.54034)] some existence theorems of solutions for equilibrium problems with lower and upper bounds are proved in noncompact topological spaces. These results further answer the open problem raised by G. Isac, V. M. Sehgal and S. P. Singh [Indian J. Math. 41, No. 1, 25–31 (1999; Zbl 1034.49005)] under much weaker assumptions.

49J40 Variational inequalities
47H10 Fixed-point theorems
91B50 General equilibrium theory
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