Browsing by Author "Romaguera, Salvador"
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Article Characterizations of quasi-metric and G-metric completeness involving w-distances and fixed points(2022) Karapınar, Erdal; Romaguera, Salvador; Tirado, Pedro; 19184nvolving w w -distances we prove a fixed point theorem of Caristi-type in the realm of (non-necessarily T 1 {T}_{1}) quasi-metric spaces. With the help of this result, a characterization of quasi-metric completeness is obtained. Our approach allows us to retrieve several key examples occurring in various fields of mathematics and computer science and that are modeled as non- T 1 {T}_{1} quasi-metric spaces. As an application, we deduce a characterization of complete G G -metric spaces in terms of a weak version of Caristi's theorem that involves a G-metric version of w-distances.Article Fixed points for cyclic orbital generalized contractions on complete metric spaces(de Gruyter Open Ltd, 2013) Karapınar, Erdal; Karapinar, Erdal; Romaguera, Salvador; Taş, Kenan; Tas, Kenan; 4971We prove a fixed point theorem for cyclic orbital generalized contractions on complete metric spaces from which we deduce, among other results, generalized cyclic versions of the celebrated Boyd and Wong fixed point theorem, and Matkowski fixed point theorem. This is done by adapting to the cyclic framework a condition of Meir-Keeler type discussed in [Jachymski J., Equivalent conditions and the Meir-Keeler type theorems, J. Math. Anal. Appl., 1995, 194(1), 293-303]. Our results generalize some theorems of Kirk, Srinavasan and Veeramani, and of Karpagam and Agrawal.