we introduce a new one-step iteration process to approximate common fixed points of twononexpansive mappings in banach spaces and prove weak convergence of the iterative sequence using (i)opial’s condition and (ii) kadec-klee property. strong convergence theorems are also established in banachspaces and uniformly convex banach spaces under the so-called condition ( a ), which is weaker thancom...

The problem considered in the paper can be described as follows. We are given a continuous mapping from one metric space into another which is regular (in the sense of metric regularity or, equivalently, controllability at a linear rate) near a certain point. How small may be an additive perturbation of the mapping which destroys regularity? The paper contains a new proof of a recent theorem of...

Let X, Y be complex vector spaces. It is shown that if a mapping f : X → Y satisfies f (x + iy) + f (x− iy) = 2f (x) − 2f (y) (0.1) or f (x + iy) − f (ix + y) = 2f (x) − 2f (y) (0.2) for all x, y ∈ X , then the mapping f : X → Y satisfies f (x + y) + f (x− y) = 2f (x) + 2f (y) for all x, y ∈ X . Furthermore, we prove the generalized Hyers-Ulam stability of the functional equations (0.1) and (0....

Let X and Y be real Banach spaces, ƒ a mapping of X into 2, y0 an element of Y It is our object in the present discussion to present a new existence theory for solutions of the equation y0£f(x) which extends, sharpens, and simplifies the corresponding theory for X — Y and ƒ hypermaximal accretive. This new existence theory is founded in a very basic way upon the fixed point theory of self-mappi...

Let K be a closed convex subset of a Banach space X and let F be a nonempty closed convex subset of K. We consider complete metric spaces of self-mappings of K which fix all the points of F and are relatively nonexpansive with respect to a given convex function f on X. We prove (under certain assumptions on f) that the iterates of a generic mapping in these spaces converge strongly to a retract...

won{gil park [won{gil park, j. math. anal. appl., 376 (1) (2011) 193{202] proved the hyers{ulam stability of the cauchy functional equation, the jensen functional equation and the quadraticfunctional equation in 2{banach spaces. one can easily see that all results of this paper are incorrect.hence the control functions in all theorems of this paper are not correct. in this paper, we correctthes...

Let K be a nonempty compact convex subset of a uniformly convex Banach space, and   K K T   : a multivalued nonexpansive mapping. We prove that the sequences of Noor iterate converge to a fixed point of T. This generalizes former results proved by Banach convergence of Noor iterates for a multi-valued mapping with a fixed point. We also introduce both of the iterative processes in a new sen...

The paper is devoted to the problem of existence of propagators for an abstract linear non-autonomous evolution Cauchy problem of hyperbolic type in separable Banach spaces. The problem is solved using the so-called evolution semigroup approach which reduces the existence problem for propagators to a perturbation problem of semigroup generators. The results are specified to abstract linear non-...