Algorithm for fixed point approximation of Fejer operators
DOI:
https://doi.org/10.17721/2706-9699.2026.1.08Keywords:
fixed point, variational inequality, optimization, Fejer operator, Halpern algorithm, strong convergenceAbstract
The theory of fixed points of operators and the corresponding algorithms are a powerful tool for studying nonlinear phenomena. The article considers the problems of finding fixed points of Fejer (quasi-nonexpansive) operators acting in Hilbert space, and variational inequalities on the set of fixed points. Strong convergence of the Halpern algorithm with averaging (the Halpern Suzuki algorithm) for finding fixed points of Fejer (quasi-nonexpansive) operators is proved.
References
1. Goebel K., Kirk W.A. Topics in metric fixed point theory. Cambridge: Cambridge University Press, 1990. 244 p.
2. Bauschke H.H., Combettes P.L. Convex Analysis and Monotone Operator Theory in Hilbert Spaces. Berlin, Heidelberg, New York: Springer, 2011. 408 p.
3. Krasnosel’skii М.А. Two remarks on the method of successive approximations. Uspekhi Mat. Nauk. 1955. Volume 10. Issue 1(63). P. 123–127.
4. Dong Q.-L., Cho Y.J., He S., Pardalos P.M., Rassias T.M. The Krasnosel’skiiMann Iterative Method: Recent Progress and Applications. Berlin, Heidelberg, New York: Springer, 2022. 127 p. https://doi.org/10.1007/978-3-030-91654-1
5. Halpern B. Fixed points of nonexpanding maps. Bull. Amer. Math. Soc. 1967. 73. P. 957–961. https://doi.org/10.1090/S0002-9904-1967-11864-0
6. Ryu E.K., Yin W. Large-Scale Convex Optimization. Algorithms and Analysis via Monotone Operators. Cambridge: Cambridge University Press, 2023. 303 p.
7. Vasin V.V., Eremin I.I. Operators and Iterative Processes of Fejer Type: Theory and Applications. Berlin: Walter de Gruyter, 2009. 155 p.
8. Semenov V., Stetsyuk P., Stovba V., Velarde Cantu J.M. One-Rank Linear Transformations and Fejer-Type Methods: An Overview. Mathematics. 2024. Volume 12. Issue 10. 1527. https://doi.org/10.3390/math12101527
9. Semenov V.V. Variational inequalities: theory and algorithms. Kyiv: Publishing and Printing Center «Kyiv University», 2021. 167 p.
10. Suzuki T. A sufficient and necessary condition for Halpern-type strong convergence to fixed points of nonexpansive mappings. Proc. of the AMS. 2007. V. 135. N. 1. P. 99–106.
11. Semenov V.V. Two methods of approximation of the fixed point of the Fejer operator. Journal of Numerical and Applied Mathematics. 2013. № 1 (111). P. 46–56.
12. Mainge P.-E. Strong Convergence of Projected Subgradient Methods for Nonsmooth and Nonstrictly Convex Minimization. Set-Valued Analysis. 2008. Vol. 16. P. 899–912. https://doi.org/10.1007/s11228-008-0102-z
13. Denysov S.V., Kovalenko O.Yu., Semenov V.V. Convergence of adaptive algorithms for equilibrium problems in Hadamard spaces. Journal of Optimization Differential Equations and their Applications.. 2025. 33 (1). P. 42–67. https://dx.doi.org/10.15421/142503
14. Lions P.-L. Approximation de points fixes de contractions. C. R. Acad. Sci. Paris, Ser. A-B. 1977. 284. P. A1357–A1359.
15. Wittmann R. Approximation of fixed points of nonexpansive mappings. Arch. Math. 1992. 58. P. 486–491. https://doi.org/10.1007/BF01190119
16. Xu H.K. Another control condition in an iterative method for nonexpansive mappings. Bull. Austral. Math. Soc. 2002. 65 P. 109–113.
17. Xu H.K. Iterative algorithms for nonlinear operators. J. London Math. Soc. 2002. 2. P. 240–256. https://doi.org/10.1112/S0024610702003332
18. Xu H.K. Viscosity approximation methods for nonexpansive mappings. J. Math. Anal. Appl. 2004. 298. P. 279–291. https://doi.org/10.1016/j.jmaa.2004.04.059
19. Lieder F. On the convergence rate of the Halpern-iteration. Optim Lett. 2021. Vol. 15. P. 405–418. https://doi.org/10.1007/s11590-020-01617-9
20. Bakushinskii A.B., Goncharskii A.V. Iterative Methods for Solving Ill-Posed Problems. Moscow: Nauka, 1989. 126 p.
21. Malitsky Yu.V., Semenov V.V. New theorems of strong convergence of the proximal method for the equilibrium programming problem. Journal of Numerical and Applied Mathematics. 2010. № 3 (102). P. 79–88.
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