• Title/Summary/Keyword: extragradient methods

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WEAK AND STRONG CONVERGENCE OF SUBGRADIENT EXTRAGRADIENT METHODS FOR PSEUDOMONOTONE EQUILIBRIUM PROBLEMS

  • Hieu, Dang Van
    • Communications of the Korean Mathematical Society
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    • v.31 no.4
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    • pp.879-893
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    • 2016
  • In this paper, we introduce three subgradient extragradient algorithms for solving pseudomonotone equilibrium problems. The paper originates from the subgradient extragradient algorithm for variational inequalities and the extragradient method for pseudomonotone equilibrium problems in which we have to solve two optimization programs onto feasible set. The main idea of the proposed algorithms is that at every iterative step, we have replaced the second optimization program by that one on a specific half-space which can be performed more easily. The weakly and strongly convergent theorems are established under widely used assumptions for bifunctions.

HALPERN TSENG'S EXTRAGRADIENT METHODS FOR SOLVING VARIATIONAL INEQUALITIES INVOLVING SEMISTRICTLY QUASIMONOTONE OPERATOR

  • Wairojjana, Nopparat;Pakkaranang, Nuttapol
    • Nonlinear Functional Analysis and Applications
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    • v.27 no.1
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    • pp.121-140
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    • 2022
  • In this paper, we study the strong convergence of new methods for solving classical variational inequalities problems involving semistrictly quasimonotone and Lipschitz-continuous operators in a real Hilbert space. Three proposed methods are based on Tseng's extragradient method and use a simple self-adaptive step size rule that is independent of the Lipschitz constant. The step size rule is built around two techniques: the monotone and the non-monotone step size rule. We establish strong convergence theorems for the proposed methods that do not require any additional projections or knowledge of an involved operator's Lipschitz constant. Finally, we present some numerical experiments that demonstrate the efficiency and advantages of the proposed methods.

A NEW METHOD FOR A FINITE FAMILY OF PSEUDOCONTRACTIONS AND EQUILIBRIUM PROBLEMS

  • Anh, P.N.;Son, D.X.
    • Journal of applied mathematics & informatics
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    • v.29 no.5_6
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    • pp.1179-1191
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    • 2011
  • In this paper, we introduce a new iterative scheme for finding a common element of the set of fixed points of a finite family of strict pseudocontractions and the solution set of pseudomonotone and Lipschitz-type continuous equilibrium problems. The scheme is based on the idea of extragradient methods and fixed point iteration methods. We show that the iterative sequences generated by this algorithm converge strongly to the common element in a real Hilbert space.

A VISCOSITY TYPE PROJECTION METHOD FOR SOLVING PSEUDOMONOTONE VARIATIONAL INEQUALITIES

  • Muangchoo, Kanikar
    • Nonlinear Functional Analysis and Applications
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    • v.26 no.2
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    • pp.347-371
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    • 2021
  • A plethora of applications from mathematical programmings, such as minimax, mathematical programming, penalization and fixed point problems can be framed as variational inequality problems. Most of the methods that used to solve such problems involve iterative methods, that is why, in this paper, we introduce a new extragradient-like method to solve pseudomonotone variational inequalities in a real Hilbert space. The proposed method has the advantage of a variable step size rule that is updated for each iteration based on previous iterations. The main advantage of this method is that it operates without the previous knowledge of the Lipschitz constants of an operator. A strong convergence theorem for the proposed method is proved by letting the mild conditions on an operator 𝒢. Numerical experiments have been studied in order to validate the numerical performance of the proposed method and to compare it with existing methods.

ON STRONG CONVERGENCE THEOREMS FOR A VISCOSITY-TYPE TSENG'S EXTRAGRADIENT METHODS SOLVING QUASIMONOTONE VARIATIONAL INEQUALITIES

  • Wairojjana, Nopparat;Pholasa, Nattawut;Pakkaranang, Nuttapol
    • Nonlinear Functional Analysis and Applications
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    • v.27 no.2
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    • pp.381-403
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    • 2022
  • The main goal of this research is to solve variational inequalities involving quasimonotone operators in infinite-dimensional real Hilbert spaces numerically. The main advantage of these iterative schemes is the ease with which step size rules can be designed based on an operator explanation rather than the Lipschitz constant or another line search method. The proposed iterative schemes use a monotone and non-monotone step size strategy based on mapping (operator) knowledge as a replacement for the Lipschitz constant or another line search method. The strong convergences have been demonstrated to correspond well to the proposed methods and to settle certain control specification conditions. Finally, we propose some numerical experiments to assess the effectiveness and influence of iterative methods.

FIXED POINT SOLUTION METHODS FOR SOLVING EQUILIBRIUM PROBLEMS

  • Anh, Pham Ngoc;Hien, Nguyen Duc
    • Bulletin of the Korean Mathematical Society
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    • v.51 no.2
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    • pp.479-499
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    • 2014
  • In this paper, we propose new iteration methods for finding a common point of the solution set of a pseudomonotone equilibrium problem and the solution set of a monotone equilibrium problem. The methods are based on both the extragradient-type method and the viscosity approximation method. We obtain weak convergence theorems for the sequences generated by these methods in a real Hilbert space.