Strong Convergence Theorems for Infinitely Nonexpansive Mappings in Hilbert Space

Let C be a nonempty closed convex subset of a Hilbert spaceH, T a self-mapping of C. Recall that T is said to be nonexpansive if ‖Tx − Ty‖ ≤ ‖x − y‖, for all x, y ∈ C. Construction of fixed points of nonexpansive mappings via Mann’s iteration 1 has extensively been investigated in literature see, e.g., 2–5 and reference therein . But the convergence about Mann’s iteration and Ishikawa’s iteration is in general not strong see the counterexample in 6 . In order to get strong convergence, one must modify them. In 2003, Nakajo and Takahashi 7 proposed such a modification for a nonexpansive mapping T . Consider the algorithm,