T Extended Weakly Contractive, Kannan, and Geraghty Mappings Fixed Points, Equivalences,

TL;DR

This paper introduces a unified framework for various classes of self-maps in metric spaces, establishing fixed point theorems and demonstrating equivalences among these classes through an auxiliary map T.

Contribution

It shows the equivalence of T-extended weakly contractive, Kannan, and Geraghty classes and clarifies the mechanism via an induced map, extending classical fixed point results.

Findings

T-extended weakly contractive class coincides with T-extended Geraghty class.

T-extended weakly Kannan class coincides with T-extended Kannan-Geraghty class.

Provides quantitative Picard convergence rates and examples including Volterra smoothing operators.

Abstract

We develop a unified T-extended framework for weakly contractive, weakly Kannan, and Geraghty classes of self-maps S on a metric space (X, d), where distances are measured on the auxiliary image via d(Tx, Ty), and the dynamics is governed by the composition of T and S. Under standard assumptions on the auxiliary map T (continuity, injectivity, subsequential convergence), fixed point theorems and Picard convergence are established for each class. The main contribution is twofold. First, it is shown that the T-extended weakly contractive class coincides with the T-extended Geraghty class, and that the T-extended weakly Kannan class coincides with the T-extended Kannan-Geraghty class. Second, the mechanism behind these equivalences is clarified by transporting the problem to an induced map F from T(X) to T(X), defined by F(Tx) = T(Sx), where the extended properties reduce exactly to the classical ones with the same control functions. A Delta-type ratio criterion on T(X) and quantitative Picard convergence rates are also provided. Examples, including Volterra smoothing operators, are presented to highlight the role of the auxiliary map. All results extend naturally to rectangular (Branciari) metric spaces.