This paper is a case study in proof mining applied to non-effective proofs in nonlinear functional anlysis. More specifically, we are concerned with the fixed point theory of nonexpansive selfmappings f of convex sets C in normed spaces. We study the Krasnoselski iteration as well as more general so-called Krasnoselski-Mann iterations. These iterations converge to fixed points of f only under s...

We show that the convergence of Mann iteration is equivalent to the convergence of Ishikawa iteration for various classes of non-Lipschitzian operators.

We establish a general theorem to approximate fixed points of Ćirić quasi-contractive operators on a normed space through the Mann iteration process with errors in the sense of Xu [10]. Our result generalizes and improves upon, among others, the corresponding results of [1,8].

We establish a general theorem to approximate fixed points of Ciric quasi-contractive operators on a generalized convex metric space through the Mann type iteration process with errors in the sense of Xu [11]. Our result generalizes and improves upon, among others, the corresponding results of [1, 8]. 2000 Mathematical Subject Classification: Primary 47H10, 47H17: Secondary 54H25

and Applied Analysis 3 We know that T is pseudocontractive if and only if T satisfies the condition 󵄩󵄩󵄩Tx − Ty 󵄩󵄩󵄩 2 ≤ 󵄩󵄩󵄩x − y 󵄩󵄩󵄩 2 + 󵄩󵄩󵄩(I − T)x − (I − T)y 󵄩󵄩󵄩 2 (15) for all x, y ∈ C. Since u ∈ Fix(T), we have from (15) that ‖Tx − u‖ 2 ≤ ‖x − u‖ 2 + ‖x − Tx‖ 2 , (16) for all x ∈ C. By using (13) and (16), we obtain 󵄩󵄩󵄩Tyn − u 󵄩󵄩󵄩 2 ≤ 󵄩󵄩󵄩yn − u 󵄩󵄩󵄩 2 + 󵄩󵄩󵄩yn − Tyn 󵄩󵄩󵄩 2 = 󵄩󵄩󵄩(1 − γn)xn + γnT...