Another look at Wang’s new method for solving split common fixed-point problems without priori knowledge of operator norms

In this paper, we give a simple proof of Wang’s recent result concerning split common fixed-point problems (F. Wang, J Fixed Point Theory Appl 19(4): 2427–2436, 2017). Moreover, we provide a more general sufficient condition than Wang’s for the weak convergence to a solution of a split common fixed-point problem.     

On split common fixed point problems

Based on the convergence theorem recently proved by the second author, we modify the iterative scheme studied by Moudafi for quasi-nonexpansive operators to obtain strong convergence to a solution of the split common fixed point problem. It is noted that Moudafi's original scheme can conclude only weak convergence. As a consequence, we obtain strong convergence theorems for split variational inequality problems for Lipschitz continuous and monotone operators, split common null point problems for maximal monotone operators, and Moudafi's split feasibility problem.     

On a Hybrid Extragradient-Viscosity Method for Monotone Operators and Fixed Point Problems

The purpose of this article is to give a more general scheme for approximating a common element of the fixed-point set of a certain mapping and the set of solutions of a variational inequality problem. This scheme is inspired by the recent work of Maingé [A hybrid extragradient-viscosity method for monotone operators and fixed point problems, SIAM J. Control Optim. 47, 1499–1515 (2008)]. We also show that some assumption imposed in his result can be relaxed. Moreover, our scheme is a genuine generalization of Maingé's result because there is a class of mappings to which our scheme is applicable, but which is beyond the scope of his result.     

Strong Convergence of the Halpern Subgradient Extragradient Method for Solving Variational Inequalities in Hilbert Spaces

Building upon the subgradient extragradient method proposed by Censor et al., we prove the strong convergence of the iterative sequence generated by a modification of this method by means of the Halpern method. We also consider the problem of finding a common element of the solution set of a variational inequality and the fixed-point set of a quasi-nonexpansive mapping with a demiclosedness property.     

On Maingé’s Approach for Hierarchical Optimization Problems

This paper aims at investigating an iterative method for solving a system of variational inequalities with fixed-point set constraints. Our scheme can be regarded as a more general variant of the algorithm proposed by Maingé. Strong convergence results are established in the setting of Hilbert spaces. We propose an alternative analysis that allows us to relax some assumption imposed in his paper for convergence of the considered method. As a complementary result, we show how to adapt these processes to the case when the constraints involve operators belonging to the class of hemi-contractive mappings; this goes beyond the scope of Maingé’s result.