Abstract
By using Gerstewitz functions, we establish a new equilibrium version of Ekeland variational principle, which improves the related results by weakening both the lower boundedness and the lower semi-continuity of the objective bimaps. Applying the new version of Ekeland principle, we obtain some existence theorems on solutions for set-valued vector equilibrium problems, where the most used assumption on compactness of domains is weakened. In the setting of complete metric spaces (Z, d), we present an existence result of solutions for set-valued vector equilibrium problems, which only requires that the domain X ⊂ Z is countably compact in any Hausdorff topology weaker than that induced by d. When (Z, d) is a Féchet space (i.e., a complete metrizable locally convex space), our existence result only requires that the domain X ⊂ Z is weakly compact. Furthermore, in the setting of non-compact domains, we deduce several existence theorems on solutions for set-valued vector equilibrium problems, which extend and improve the related known results.
Similar content being viewed by others
References
Ansari, Q. H.: Vector form of Ekeland-type variational principle with applications to vector equilibrium problems and fixed point theory. J. Math. Anal. Appl., 334, 561–575 (2007)
Al-Homidan, S., Ansari, Q. H., Yao, J. C.: Some generalizations of Ekeland-type variational principle with applications to equilibrium problems and fixed point theory. Nonlinear Anal., 69, 126–139 (2008)
Alleche, B., Rădulescu, V. D.: The Ekeland variational principle for equilibrium problems revisited and applications. Nonlinear Anal.: Real World Appl., 23, 17–25 (2015)
Ansari, Q. H., Konnov, I. V., Yao, J. C.: On generalized vector equilibrium problems. Nonlinear Anal., 47, 543–554 (2001)
Ansari, Q. H., Yao, J. C.: An existence result for generalized vector equilibrium problems. Applied Math. Letters, 12, 53–56 (1999)
Bianchi, M., Kassay, G., Pini, R.: Existence of equilibria via Ekeland’s principle. J. Math. Anal. Appl., 305, 502–512 (2005)
Blum, E., Oettli, W.: From optimization and variational inequalities to equilibrium problems. Math. Student, 63, 123–145 (1994)
Bao, T. Q., Mordukhovich, B. S.: Variational principles for set-valued mappings with applications to multiobjective optimization. Control Cybernet, 36, 531–562 (2007)
Bao, T. Q., Mordukhovich, B. S.: Relative Pareto minimizers for multiobjective problems: Existence and optimality conditions. Math. Program, 122, 301–347 (2010)
Bednarczuk, E. M., Zagrodny, D.: Vector variational principle. Arch. Math. (Basel), 93, 577–586 (2009)
Bianchi, M., Kassay, G., Pini, R.: Ekeland’s principle for vector equilibrium problems. Nonlinear Anal., 66, 1459–1464 (2007)
Bianchi, M., Hadjisavvas, N., Schaible, S.: Vector equilibrium problems with generalized monotone bifunctions. J. Optim. Theory Appl., 92, 527–542 (1997)
Chen, G. Y., Huang, X. X., Yang, X. G.: Vector Optimization: Set-Valued and Variational Analysis, Springer-Verlag, Berlin, 2005
Chen, G. Y., Huang, X. X.: A unified approach to the existing three types of variational principle for vector valued functions. Math. Methods Oper. Res., 48, 349–357 (1998)
Chen, G. Y., Huang, X. X.: Ekeland’s ϵ-variational principle for set-valued mappings. Math. Meth. Oper. Res., 48, 181–186 (1998)
Chen, Y., Cho, Y. J., Yang, L.: Note on the results with lower semi-continuity. Bull. Korean Math. Soc., 39, 535–541 (2002)
Dentcheva, D., Helbig, S.: On variational principles, level sets, well-posedness, and ϵ-solutions in vector optimization. J. Optim. Theory Appl., 89, 325–349 (1996)
Du, W. S.: On some nonlinear problems induced by an abstract maximal element principle. J. Math. Anal. Appl., 347, 391–399 (2008)
Ekeland, I: On the variational principle. J. Math. Anal. Appl., 47, 324–353 (1974)
Ekeland, I: Nonconvex minimization problems. Bull. Amer. Math. Soc., 1, 443–474 (1979)
Finet, C., Quarta L., Troestler, C.: Vector-valued variational principles. Nonlinear Anal., 52, 197–218 (2003)
Flores-Bazán, F., Gutiérrez, C., Novo, V.: A Brézis–Browder principle on partially ordered spaces and related ordering theorems. J. Math. Anal. Appl., 375, 245–260 (2011)
Farkas, C., Molnár, A. E.: A generalized variational principle and its application to equilibrium problems. J. Optim. Theory Appl., 156, 213–231 (2013)
Göpfert, A., Riahi, H., Tammer, C., et al.: Variational Methods in Partially Ordered Spaces, Springer-Verlag, New York, 2003
Gong, X.: Ekeland’s principle for set-valued vector equilibrium problems. Acta Math. Sci., 34B, 1179–1192 (2014)
Göpfert, A., Tammer C., Zălinescu, C.: On the vectorial Ekeland’s variational principle and minimal point theorems in product spaces. Nonlinear Anal., 39, 909–922 (2000)
Gutiérrez, C., Jiménez, B., Novo, V.: A set-valued Ekeland’s variational principle in vector optimization. SIAM J. Control. Optim., 47, 883–903 (2008)
Ha, T. X. D.: Some variants of the Ekeland variational principle for a set-valued map. J. Optim. Theory Appl., 124, 187–206 (2005)
Hamel, A. H.: Equivalents to Ekeland’s variational principle in uniform spaces. Nonlinear Anal., 62, 913–924 (2005)
He, F., Qiu, J. H.: Sequentially lower complete spaces and Ekeland’s variational principle. Acta Math. Sin., Engl. Ser., 31, 1289–1302 (2015)
Horváth, J.: Topological Vector Spaces and Distributions, vol. 1, Addison-Wesley, Reading, MA, 1966
Khanh, P. Q., Quy, D. N.: On generalized Ekeland’s variational principle and equivalent formulations for set-valued mappings. J. Glob. Optim., 49, 381–396 (2011)
Khanh, P. Q., Quy, D. N.: Versions of Ekeland’s variational principle involving set perturbations. J. Glob. Optim., 57, 951–968 (2013)
Kassay, G.: On equilibrium problems, in: A. Chinchuluun, P. M. Padalos, R. Enkhbat, I. Tseveendorj (Eds.), Optimization and Optimal Control: Theory and Applications, in: Optimization and its Applications, 39, Springer, 55–83 (2010)
Kelley, J. L., Namioka, I., Donoghue, W. F., et al.: Linear Topological Spaces, Van Nostrand, Princeton, 1963
Köthe, G.: Topological Vector Spaces I, Springer-Verlag, Berlin, 1969
Konnov, I. V., Yao, J. C.: Existence of solutions for generalized vector equilibrium problems. J. Math. Anal. Appl., 233, 328–335 (1999)
Liu, C. G., Ng, K. F.: Ekeland’s variational principle for set-valued functions. SIAM J. Optim., 21, 41–56 (2011)
Lin, L. J., Du, W. S.: Ekeland’s variational principle, minimax theorems and existence of nonconvex equilibria in complete metric spaces. J. Math. Anal. Appl., 323, 360–370 (2006)
Németh, A. B.: A nonconvex vector minimization problem. Nonlinear Anal., 10, 669–678 (1986)
Oettli, W., Théra, M.: Equivalents of Ekeland’s principle. Bull. Austral Math. Soc., 48, 385–392 (1993)
Qiu, J. H.: A generalized Ekeland vector variational principle and its applications in optimization. Nonlinear Anal., 71, 4705–4717 (2009)
Qiu, J. H.: On Ha’s version of set-valued Ekeland’s variational principle. Acta Math. Sin., Engl. Ser., 28, 328–335 (2012)
Qiu, J. H.: Set-valued quasi-metrics and a general Ekeland’s variational principle in vector optimization. SIAM J. Control Optim., 51, 1350–1371 (2013)
Qiu, J. H.: A pre-order principle and set-valued Ekeland variational principle. J. Math. Anal. Appl., 419, 904–937 (2014)
Qiu, J. H.: An equilibrium version of vectorial Ekeland variational principle and its applications to equilibrium problems. Nonlinear Anal. Real World Applications, 27, 26–42 (2016)
Qiu, J. H., Li, B., He, F.: Vectorial Ekeland’s variational principle with a w-distance and its equivalent theorems. Acta Math. Sci., 32B, 2221–2236 (2012)
Tammer, C.: A generalization of Ekeland’s variational principle. Optimization, 25, 129–141 (1992)
Tammer, C., Zălinescu, C.: Vector variational principle for set-valued functions. Optimization, 60, 839–857 (2011)
Wilansky, A.: Modern Methods in Topological Vector Spaces, McGraw-Hill, New York, 1978
Zeng, J., Li, S. J.: An Ekeland’s variational principle for set-valued mappings with applications. J. Computational and Applied Math., 230, 477–484 (2009)
Zhu, J., Wei, L., Zhu, C. C.: Caristi type coincidence point theorem in topological spaces. J. Applied Math., 2013 ID 902692 (2013)
Zhu, J., Zhong, C. K., Cho, Y. J.: A generalized variational principle and vector optimization. J. Optim. Theory Appl., 106, 201–218 (2000)
Author information
Authors and Affiliations
Corresponding author
Additional information
Supported by National Natural Science Foundation of China (Grant Nos. 11471236 and 11561049)
Rights and permissions
About this article
Cite this article
Qiu, J.H. An equilibrium version of set-valued Ekeland variational principle and its applications to set-valued vector equilibrium problems. Acta. Math. Sin.-English Ser. 33, 210–234 (2017). https://doi.org/10.1007/s10114-016-6184-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10114-016-6184-x
Keywords
- Ekeland variational principle
- set-valued vector equilibrium problem
- quasi-ordered locally convex space
- lower semi-continuity
- lower boundedness