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Article Citation - WoS: 5Citation - Scopus: 5Mild Solutions for Conformable Fractional Order Functional Evolution Equations Via Meir-Keeler Type Fixed Point Theorem(Univ Nis, Fac Sci Math, 2025) Berrighi, Fatma; Medjadj, Imene; Karapinar, ErdalIn this study, we delve into the realm of mild solutions for conformable fractional order functional evolution equations, focusing on cases where the fractional order is strictly greater than 1 and less than 2 within a separable Banach space. We demonstrate the existence, uniqueness, attractivity, and controllability of these solutions under local conditions. Our approach involves leveraging a contribution of Meir-Keeler's fixed point theorem alongside the principle of measures of noncompactness. To demonstrate the practical ramifications of our theoretical finds, we provide a specific example that underscores the relevance and applications of the established results.Article Citation - WoS: 25Citation - Scopus: 32Fixed Point Theorems in Complete Modular Metric Spaces and an Application To Anti-Periodic Boundary Value Problems(Univ Nis, Fac Sci Math, 2017) Aksoy, Umit; Karapinar, Erdal; Erhan, Inci M.In this paper existence and uniqueness of fixed points for a general class of contractive and nonexpansive mappings on modular metric spaces is discussed. As an application of the theoretical results, the existence of a solution of anti-periodic boundary value problems for nonlinear first order differential equations of Caratheodory's type is considered in the framework of modular metric spaces.Article Sturmian Comparison Theory for Half-Linear and Nonlinear Differential Equations Via Picone Identity(Univ Nis, Fac Sci Math, 2017) Ozbekler, AbdullahIn this paper, Sturmian comparison theory is developed for the pair of second order differential equations; first of which is the nonlinear differential equations of the form (m(t)Phi(beta) (y'))' + Sigma (n) (i = 1) qi(t)Phi(alpha i) (y) = 0 and the second is the half-linear differential equations (k(t)Phi(beta) (x'))' + p(t) Phi(beta) (x) = 0 where Phi(*)(s) = \ s \(*-1)s and alpha(1) > . . .> alpha(m) > beta > alpha(m + 1) > . . . > alpha(n) > 0. Under the assumption that the solution of Eq. (2) has two consecutive zeros, we obtain Sturm-Picone type and Leighton type comparison theorems for Eq. (1) by employing the new nonlinear version of Picone's formula that we derive. Wirtinger type inequalities and several oscillation criteria are also attained for Eq. (1). Examples are given to illustrate the relevance of the results.Article Citation - WoS: 6Citation - Scopus: 9On Interpolative Metric Spaces(Univ Nis, Fac Sci Math, 2024) Karapinar, ErdalThe purpose of this article is to expand the "open discussion" on the definition and necessity of the interpolation metric space and keep it on the agenda of researchers in nonlinear functional analysis. The secondary aim of this article is to indicate that the outcomes of this "open discussion" have the potential to stop the recent recession in the metric fixed point theory.Article A Note on the Structure of Interpolative Metric Spaces(Univ Nis, Fac Sci Math, 2025) Karapinar, Erdal; Romaguera, SalvadorIn this note we observe that interpolative metric spaces lie between strong b-metric spaces and b-metric spaces. This paper aims to comprehend the connections of these notions and the corresponding structures, namely, interpolative metric spaces, strong b-metric spaces, and b-metric spaces. An example is considered to illustrate our claims.Article Citation - WoS: 10Citation - Scopus: 12A Note on Meir-Keeler Contractions on Dislocated Quasi-b-metric(Univ Nis, Fac Sci Math, 2017) Karapinar, ErdalIn this manuscript, we show that Meir-Keeler type contractions posses a fixed point in the setting of dislocated quasi-b-metricArticle Citation - WoS: 28Citation - Scopus: 33Ciric Type Nonunique Fixed Point Theorems on b-metric Spaces(Univ Nis, Fac Sci Math, 2017) Alsulami, Hamed H.; Karapinar, Erdal; Rakocevic, VladimirIn this paper, inspired the very interesting results of Ciric [20], we investigate the existing non-unique fixed points of certain operators in the context of b-metric spaces. Our main results unify and cover several existing results on the topic in the literature.
