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A large number of nonlinear and optimization problems can be reduced to altering point problems. This paper aims to introduce the parallel normal S-iteration technique and study its convergence rates for solving such problems in infinite-dimensional Hilbert spaces under practical assumptions. We place particular emphasis on the parallel splitting method for the sum of two maximal monotone operators and that can apply for solving a class of convex composite minimization problems. Moreover, we present applications of our iterative methods to some nonlinear problems, such as a system of variational inequalities and a system of inclusion problems. Finally, to demonstrate the applicability of the altering point technique, the performances of our proposed parallel normal S-iteration methods are presented through numerical experiments in signal recovery problems. [ABSTRACT FROM AUTHOR]

Halpern's iteration method, discovered by Halpern in 1967, is an iterative algorithm for finding fixed points of a nonexpansive mapping in Hilbert and Banach spaces. Since many optimization problems can be cast into fixed point problems of nonexpansive mappings, Halpern's method plays an important role in optimization methods. This paper discusses recent advances in convergence and rate of convergence results of Halpern's method, and applications in optimization problems, including variational inequalities, monotone inclusions, Douglas-Rachford splitting method, and minimax problems. [ABSTRACT FROM AUTHOR]

Professor Wataru Takahashi, born in Tokyo in 1944, received Bachelor's degree from Yokohama National University in 1966 and Doctorate of Science degree from Tokyo Institute of Technology (Tokyo Tech) in 1971 under the supervision of Professor H. Umegaki. Wataru took the position of an Assistant Professor in the Department of Information Science at Tokyo Tech in April 1971, and moved, as an Associate Professor, to the Faculty of Education at Yokohama National University in April 1972. Professor Wataru Takahashi (January 22, 1944-November 19, 2020) This special issue, titled "Fixed Point Theory and Nonlinear Functional Analysis", is dedicated to the memory of Professor Wataru Takahashi who passed away on November 19, 2020, at the age of 76. [Extracted from the article]

A new iterative method for finding a zero of m-accretive operators is proposed. This method, involving a so-called perturbed mapping, provides a way to construct sunny nonexpansive retractions. Several strong convergence theorems for this method are established in a Banach space that is either uniformly smooth or reflexive with a weakly continuous duality map. [ABSTRACT FROM AUTHOR]

The aim of this paper is to generalize the results of Yamada et al. [Yamada, I., Ogura, N., Yamashita, Y., Sakaniwa, K. (1998). Quadratic approximation of fixed points of nonexpansive mappings in Hilbert spaces. Numer. Funct. Anal. Optimiz. 19(l):165-190], and to provide complementary results to those of Deutsch and Yamada [Deutsch, F., Yamada, I. (1998). Minimizing certain convex functions over the intersection of the fixed point sets of nonexpansive mappings. Numer. Funct. Anal. Optim. 19(1&2):33-56] in which they consider the minimization of some function d over a closed convex set F, the nonempty intersection of N fixed point sets. We start by considering a quadratic function θ and providing a relaxation of conditions of Theorem 1 of Yamada et al. (1998) to obtain a sequence of fixed points of certain contraction maps, converging to the unique minimizer of θ over F. We then extend Theorem 2 and obtain a complementary result to Theorem 3 of Yamada et al. (1998) by replacing the condition lim n → ∞ (λn - λn+1)/λ²n+1 = 0 on the parameters by the more general condition lim n → ∞ λn / λn+1 = 1. We next look at minimizing a more general function θ than a quadratic function which was proposed by Deutsch and Yamada (1998) and show that the sequence of fixed points of certain maps converge to the unique minimizer of 9 over F. Finally, we prove a complementary result to that of Deutsch and Yamada (1998) by using the alternate condition on the parameters. [ABSTRACT FROM AUTHOR]

Let G be a nonempty closed (resp. bounded closed) subset in a strongly convex Banach space X. Let denote the space of all nonempty bounded closed subsets of X endowed with the Hausdorff distance and let denote the closure of the set . We prove that Eo(G) (resp. Eo(G)), the set of all (resp. ) such that the minimization (resp. maximization) problem min(A, G) (resp. ) is well-posed, is residual in (resp. ). [ABSTRACT FROM AUTHOR]

We prove the convergence of an implicit iteration process to a common fixed point of a finite family of nonexpansive mappings in a Hilbert space. [ABSTRACT FROM AUTHOR]