M. A. Khamsi

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One of the fundamental and celebrated results in the theory of nonexpansive mappings is Browder’s demiclosed principle 1 which states that if X is a uniformly convex Banach space, then C is a nonempty closed convex subset of X, and if T : C → X is a nonexpansive mapping, then I−T is demiclosed at each y ∈ X, that is, for any sequence {xn} inC conditions xn(More)
The existence of approximate fixed points and approximate endpoints of the multivalued almost I-contractions is established. We also develop quantitative estimates of the sets of approximate fixed points and approximate endpoints for multivalued almost I-contractions. The proved results unify and improve recent results of Amini-Harandi 2010 , M. Berinde and(More)
In this paper, we show that nonempty closed convex subsets of a metric tree enjoy many properties shared by convex subsets of Hilbert spaces and admissible subsets of hyperconvex spaces. Furthermore, we prove that a set valued mapping T ∗ of a metric tree M with convex values has a selection T : M → M for which d(T (x), T (y)) ≤ dH(T ∗(x), T ∗(y)) for each(More)
Let X, d be a metric space and x, y ∈ X with l d x, y . A geodesic path from x to y is an isometry c : 0, l → X such that c 0 x and c l y. The image of a geodesic path is called a geodesic segment. A metric spaceX is a (uniquely) geodesic space if every two points ofX are joined by only one geodesic segment. A geodesic triangle x1, x2, x3 in a geodesic(More)