Invariant approximations, generalized I-contractions, and R-subweakly commuting maps

Invariant Approximations, Generalized I-contractions, and R-subweakly Commuting Maps

Let S be a subset of a normed space X = (X ,‖ · ‖) and T and I self-mappings of X . Then T is called (1) nonexpansive on S if ‖Tx− Ty‖ ≤ ‖x− y‖ for all x, y ∈ S; (2) Inonexpansive on S if ‖Tx − Ty‖ ≤ ‖Ix − I y‖ for all x, y ∈ S; (3) I-contraction on S if there exists k ∈ [0,1) such that ‖Tx − Ty‖ ≤ k‖Ix − I y‖ for all x, y ∈ S. The set of fixed points of T (resp., I) is denoted by F(T) (resp., ...

Common fixed points and invariant approximations of pointwise R - subweakly commuting maps on nonconvex sets

In this paper we prove a theorem giving sufficient conditions for the existence of common fixed points of pointwise R-subweakly commuting mappings on nonconvex sets. We apply this theorem to derive some results on the existence of common fixed points from the set of best approximation for this class of maps in the set up of metric spaces. The results proved in the paper generalize and extend so...

Cq-COMMUTING MAPS AND INVARIANT APPROXIMATIONS

Let X be a linear space. A p-norm on X is a real-valued function on X with 0 < p ≤ 1, satisfying the following conditions: (i) ‖x‖p ≥ 0 and ‖x‖p = 0⇔ x = 0, (ii) ‖αx‖p = |α|p‖x‖p, (iii) ‖x+ y‖p ≤ ‖x‖p +‖y‖p, for all x, y ∈ X and all scalars α. The pair (X ,‖ · ‖p) is called a p-normed space. It is a metric linear space with a translation invariant metric dp defined by dp(x, y)= ‖x− y‖p for all ...

Common Fixed Points and Invariant Approximations for Cq-commuting Generalized nonexpansive mappings

Some common fixed point theorems for Cq-commuting generalized nonexpansive mappings have been proved in metric spaces. As applications, invariant approximation results are also obtained. The results proved in the paper extend and generalize several known results including those of M. Abbas and J.K. Kim [Bull. Korean Math. Soc. 44(2007) 537-545], I. Beg, N. Shahzad and M. Iqbal [Approx. Theory A...

Common Fixed Points, Invariant Approximation and Generalized Weak Contractions