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Using the approach of so-called c-sequences introduced by the fifth author in his recent work, we give much simpler and shorter proofs of multivalued Perov's type results with respect to the ones presented in the recently published paper by M. Abbas et al. Our proofs improve, complement, unify and enrich the ones from the recent papers. Further, in the last section of this paper, we correct and generalize the well-known Perov's fixed point result. We show that this result is in fact equivalent to Banach's contraction principle.

The objective of this article is to introduce function weighted L-R-complete dislocated quasi-metric spaces and to present fixed point results fulfilling generalized rational type F-contraction for a multivalued mapping in these spaces. A suitable example confirms our results. We also present an application for a generalized class of nonlinear integral equations. Our results generalize and extend the results of Karapınar et al. (IEEE Access 7:89026–89032, 2019).

In this article, the notions of partially continuous mappings, partially bounded, partially compact and partially closed sets of an ordered E-metric space are defined. These notions are used to introduce partial E-measure of noncompactness and prove the fixed point results of monotone mappings and sum of two monotone mappings. In this way we generalize many results including the well known results of Schauder, Darbo and Krasnoselskii, in the settings of ordered E-metric and ordered Banach spaces. We also provide nontrivial examples and existence results for a class of integral equations to validate the significance of our theory and results.

We concern this manuscript with Geraghty type contraction mappings via simulation functions and pull down some sufficient conditions for the existence and uniqueness of point of coincidence for several classes of mappings involving Geraghty functions in the setting of metric spaces. These findings touch up many of the existing results in the literature. Additionally, we elicit one of our main result by a non-trivial example and pose an interesting open problem for the enthusiastic readers.

Introduction/purpose: This paper considers, generalizes and improves recent results on fixed points in rectangular metric spaces. The aim of this paper is to provide much simpler and shorter proofs of some new results in rectangular metric spaces. Methods: Some standard methods from the fixed point theory in generalized metric spaces are used. Results: The obtained results improve the well-known results in the literature. The new approach has proved that the Picard sequence is Cauchy in rectangular metric spaces. The obtained results are used to prove the existence of solutions to some nonlinear problems related to chemical sciences. Finally, an open question is given for generalized contractile mappings in rectangular metric spaces. Conclusions: New results are given for fixed points in rectangular metric spaces with application to some problems in chemical sciences.

In this paper, we introduce the notions of Z?-ontractions and Suzuki Z?-contractions via ?-simulation functions. By using these new contractions, we extend and unify several existing fixed point results in the corresponding literature. We also show that the recently defined notion of L-simulation function is an special case of Z?-contraction. In addition, some notable examples are given to illustrate and support the obtained results.

We compare the newly defined bv(s)-metric spaces with several other abstract spaces like metric spaces, b-metric spaces and show that some well-known results, which hold in the latter class of spaces, may not hold in bv(s)-metric spaces. Besides, we introduce the notions of sequential compactness and bounded compactness in the framework of bv(s)-metric spaces. Using these notions, we prove some fixed point results involving Nemytzki–Edelstein type mappings in this setting, from which several comparable fixed point results can be deduced. In addition to these, we find some existence and uniqueness criteria for the solution to a certain type of mixed Fredholm–Volterra integral equations.

Introduction/purpose: This paper establishes some new results of Piri-Kumam-Dung-type mappings in a complete metric space.The goal was to improve the already published results. Methods: Using the property of a strictly increasing function as well as the known Lemma formulated in (Radenović et al, 2017), the authors have proved that a Picard sequence is a Cauchy sequence. Results: New results were obtained concerning the F-contraction mappings of S in a complete metric space. To prove it, the authors used only property (W1). Conclusion:The authors believe that the obtained results represent a significant improvement of many known results in the existing literature.

Z. D. Mitrović and S. Radenović introduced in [The Banach and Reich contractions in bv (s)-metric spaces, J. Fixed Point Theory Appl. 19 (2017), 3087–3095] a new class of generalized metric spaces and proved some fixed point theorems in this framework. The purpose of this paper is to consider other kinds of contractive mappings in bv (s)-metric spaces, and show how the work in the new settings differs from the one in standard metric and b-metric spaces. Examples show the usefulness of the obtained results.

The aim of this work is to establish fixed point theorems under rational type contractions in the framework of complex-valued metric spaces. These theorems extend and generalize some prominent results in the present literature. Furthermore, as an application the existence result is given for the system of Volterra–Hammerstein non-linear integral equations.

We initiate the notion of generalized MT- cyclic contraction mappings with respect to an auxiliary function φ and investigate the existence of a best proximity point of such mappings in the setting...

The principal results in this article deal with the existence of fixed points of a new class of generalized F-contraction. In our approach, by visualizing some non-trivial examples we will obtain better geometrical interpretation. Our main results substantially improve the theory of F-contraction mappings and the related fixed point theorems. In section-4, application to graph theory is entrusted and proved results are endorsed by an example through graph. The presented new techniques give the possibility to justify the existence problems of the solutions for some class of integral equations. For the future aspects of our study, an open problem is suggested regarding discretized population balance model, whose solution may be derived from the established techniques.

We present some new results for ??L-rational contractive and cyclic ??L- rational contractive mappings defined in dl-complete metric-like spaces (also known as dislocated metric spaces). We have showed that established results for both types of contractive mappings are in the fact equivalent. By using this result obtained so far we discuss some examples at the end of this paper. All these examples show the advantage of our results.

In this paper we consider cyclic (s-q)-Dass-Gupta-Jaggi type contractive mapping in b-metric like spaces. By using our new approach for the proof that one Picard?s sequence is Cauchy in the context of b-metric-like space, our results generalize, improve and complement several results in the existing literature. Moreover, we showed that the cyclic type results of Kirk et al. are equivalent with the corresponding usual fixed point ones for Dass-Gupta-Jaggi type contractive mappings. Finally, some examples are presented here to illustrate the usability of the obtained theoretical results.

The notion of nonlinear $(\mathcal{F}_{s}, \mathcal{L})$(Fs,L)-contractive multivalued operators is initiated and some related fixed point results are considered. We also give an example to show the validity of obtained theoretical results. Our results generalize many existing ones in the literature.

In this manuscript, we establish two Wardowski–Feng–Liu-type fixed point theorems for orbitally lower semicontinuous functions defined in orbitally complete b-metric spaces. The obtained results generalize and improve several existing theorems in the literature. Moreover, the findings are justified by suitable nontrivial examples. Further, we also discuss ordered version of the obtained results. Finally, an application is presented by using the concept of fractal involving a certain kind of fractal integral equations. An illustrative example is presented to substantiate the applicability of the obtained result in reducing the energy of an antenna.

The purpose of this paper is to establish the uniqueness and existence of the common fixed point under generalized contractive conditions in [Formula: see text]-metric spaces with supportive examples. We also approximate the common fixed point by Jungck–Picard and Picard iteration procedures along with the [Formula: see text] property of the mappings. Further, [Formula: see text]-stability of Jungck–Picard iterative and [Formula: see text]-stability of Picard iterative schemes are proved.

In this paper, we introduce a notion of convex F-contraction and establish some fixed point results for such contractions in b-metric spaces. Moreover, we give a supportive example to show that our convex F-contraction is quite different from the F-contraction used in the existing literature since our convex F-contraction does not necessarily contain the continuous mapping but the F-contraction contains such mapping. In addition, via some facts, we claim that our results indeed generalize and improve some previous results in the literature.

The terms of F&minus, integral contraction as well as (&piv, &zeta, &tilde, F,i)&minus, integral contraction are introduced. Fixed point and common fixed point theorems are established. For the mapping F we use only the supposition that it is strictly increasing. As a consequence of the main theorems we obtain Jungck&ndash, Wardowski, Branciari&ndash, Wardowski and Jungck&ndash, Branciari type results. Consequently, the results presented in the article enhance and complement some known results in literature.

One of the main goals of this paper is to obtain new contractive conditions using the method of a strictly increasing mapping F:(0,+∞)→(−∞,+∞). According to the recently obtained results, this was possible (Wardowski’s method) only if two more properties (F2) and (F3) were used instead of the aforementioned strictly increasing (F1). Using only the fact that the function F is strictly increasing, we came to new families of contractive conditions that have not been found in the existing literature so far. Assuming that α(u,v)=1 for every u and v from metric space Ξ, we obtain some contractive conditions that can be found in the research of Rhoades (Trans. Amer. Math. Soc. 1977, 222) and Collaco and Silva (Nonlinear Anal. TMA 1997). Results of the paper significantly improve, complement, unify, generalize and enrich several results known in the current literature. In addition, we give examples with results in line with the ones we obtained.

Within this manuscript we generalize the two recently obtained results of O. Popescu and G. Stan, regarding the F-contractions in complete, ordinary metric space to 0-complete partial metric space and 0-complete metric-like space. As Popescu and Stan we use less conditions than D. Wardovski did in his paper from 2012, and we introduce, with the help of one of our lemmas, a new method of proving the results in fixed point theory. Requiring that the function F only be strictly increasing, we obtain for consequence new families of contractive conditions that cannot be found in the existing literature. Note that our results generalize and complement many well-known results in the fixed point theory. Also, at the end of the paper, we have stated an application of our theoretical results for solving fractional differential equations. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

In this paper, we consider, discuss, complement, improve, generalize, and enrich some fixed point results obtained forβ−ψ1−ψ2−contractive conditions in ordered b-metric-like spaces. By using our new approach for the proof that one Picard’s sequence isbbl−Cauchy in the context of b-metric-like spaces, we get much shorter proofs than the ones mentioned in the recent papers. Also, by the use of our method, we complement and enrich some common fixed point results forβq,ϕs,ψ−contraction mappings. Our approach in this paper generalizes and modifies several comparable results in the existing literature.

Many authors used the concept of F&minus, contraction introduced by Wardowski in 2012 in order to define and prove new results on fixed points in complete metric spaces. In some later papers (for example Proinov P.D., J. Fixed Point Theory Appl. (2020)22:21, doi:10.1007/s11784-020-0756-1) it is shown that conditions (F2) and (F3) are not necessary to prove Wardowski&rsquo, s results. In this article we use a new approach in proving that the Picard&ndash, Jungck sequence is a Cauchy one. It helps us obtain new Jungck&ndash, Fisher&ndash, Wardowski type results using Wardowski&rsquo, s condition (F1) only, but in a way that differs from the previous approaches. Along with that, we came to several new contractive conditions not known in the fixed point theory so far. With the new results presented in the article, we generalize, extend, unify and enrich methods presented in the literature that we cite.

In the paper, we consider some fixed point results of F-contractions for triangular α-admissible and triangular weak α-admissible mappings in metric-like spaces. The results on F-contraction type mappings in the context of metric-like spaces are generalized, improved, unified, and enriched. We prove the main result but using only the property (F1) of the strictly increasing mapping F:0,+∞→−∞,+∞. Our approach gives a proper generalization of several results given in current literature.

In this paper we consider the Green function for a boundary value problem of generic order. For a specific case, the Leray–Schauder form of the fixed point theorem has been used to prove the existence of a solution for this particular equation. Our theoretical approach generalizes, extends, complements, and enriches several results in the existing literature.

We present a survey of various variants of fixed point results for single- and multivalued mappings, under conditions of the type first used by Pata (J Fixed Point Theory Appl 10:299–305, 2011). A number of examples are given, showing the effectiveness of these results. Some recent misinterpretations of the use of Pata-type conditions are commented.

A new convergence criteria using the concept of semi-interior points has been defined in E-metric spaces with non-solid and non-normal set of positive elements $$E^{+}$$ of a real normed space E, also known as a positive cone. Many examples are provided to insure the existence of semi-interior points of $$E^{+}$$ with empty interior. New generalizations of Banach, Kannan and Chatterjea fixed point theorems are proved.

In this note, we discuss, improve and complement some recent results of the conformable fractional derivative introduced and established by Katugampola[arxiv:1410.6535v1] and Khalil et al. [J. Comput. Appl. Math. 264(2014) 65-70]. Among other things we show that each function $f$ defined on $(a,b)$, $a>0$ has a conformable fractional derivative (CFD) if and only if it has a classical first derivative. At the end of the paper, we prove the Rolle's, Cauchy, Lagrange's and Darboux's theorem in the context of Conformable Fractional Derivatives.

This paper consists of several fixed point theorems in the fuzzy b-metric spaces. As an important result, we give a sufficient condition for a sequence to be Cauchy in the fuzzy b-metric space. Thus we simplify the proofs of many fixed point theorems in the fuzzy b-metric spaces with the well-known contraction conditions.

The purpose of this paper is to present some new fixed point results in the generalized metric spaces of Perov’s sense under a contractive condition of Hardy–Rogers type. The data dependence of the fixed point set, the well-posedness of the fixed point problem and the Ulam–Hyers stability are also studied. Author Manuel de la Sen thanks the Basque Government for its support of this work through Grant IT1207-19

The purpose of this paper is to introduce and analyze a new idea of proximally compatible mappings and we extend some results of Jungck via proximally compatible mappings. Furthermore, we obtain common best proximity point theorems for proximally compatible mappings through two different ways of construction of sequences. In addition, we provide an example to support our main result. This work has been partially funded by Basque Government through Grant IT1207-19.

New fixed point and coupled fixed point theorems in partially ordered ν-generalized metric spaces are presented. Since the product of two ν-generalized metric spaces is not in general a ν-generalized metric space, a different approach is needed than in the case of standard metric spaces.

This article surveys many of the recent works regarding simulation functions and $$\mathcal {Z}$$ -contractions that came into existence after the publication of Khojasteh et al. (Filomat 29(6):1189–1194, 2015). These results assess inclusive of simulation functions, $$\mathcal {Z}$$ -contractions, b-simulation functions, Suzuki-type $$\mathcal {Z}$$ -contractions, Darbo’s fixed point theorem, $$\alpha $$ -admissible $$\mathcal {Z}$$ -contractions, first-order periodic problems and variational inequality problems. Additionally, we consider many of the metric frameworks that have been taken into account while exploring the results.

This note is intended as an attempt at presenting some topological properties in cone metric spaces over Banach algebras. Moreover, the corresponding fixed point results are given. In addition, the P property, T-stability of Picard’s iteration, well-posedness of fixed point problems are also displayed. Our results complement and generalize some previous results in the existing literature.

In this paper by using of Suzuki-type approach we introduce the new contractive condition in the framework of non-Archimedean fuzzy metric spaces. We prove also the corresponding coincidence fixed point theorem for two mappings in this framework. Finally, two examples are presented to verify the effectiveness and applicability of our main results.

In this paper we have given a proof for Fisher contraction principle in b-metric spaces with increased range of the Lipschitzian constants and without continuity of the b-metric function, to generalize some of the results proved in Jovanovic et al. (Fixed Point Theory Appl, 2010) and many others. Simple example is given to illustrate the validity and superiority of our results. As the applications of our results, we obtain fixed point theorems of Jungck and Banach in b-metric spaces.

In this paper, we introduce a new generalized distance, namely the $$w_0$$ -distance, which is a special type of w-distance. By using the concept of $$w_0$$ -distance, we generalize some recent best proximity point results involving simulation functions. As a consequence, several best proximity point theorems are obtained. We support our results with examples.

In this paper, we obtain some sufficient conditions for the existence and uniqueness of point of coincidence by using simulation functions in the context of metric spaces and prove some interesting results. Our results generalize the corresponding results of [5, 8, 13, 14, 16] in several directions. Also, we provide an example which shows that our main result is a proper generalization of the result of Jungck [American Math. Monthly 83(1976) 261-263], L-de-Hierro et al. [J. Comput. Appl. Math 275(2015) 345-355] and of Olgun et al. [Turk. J. Math. (2016) 40:832-837].

Based on the concepts of ?-proximal admissible mappings and simulation function, we establish some best proximity point and coupled best proximity point results in the context of b-complete b-metric spaces. We also provide some concrete examples to illustrate the obtained results. Moreover, we prove the existence of the solution of nonlinear integral equation and positive definite solution of nonlinear matrix equation X = Q + ?m,i=1 A*i?(X)Ai-?m,i=1 B*i(X)Bi. The given results not only unify but also generalize a number of existing results on the topic in the corresponding literature.

A dislocated cone metric space over Banach algebra is introduced as a generalisation of a cone metric space over Banach algebra as well as a dislocated metric space. Fixed point theorems for Perov-type α-quasi contraction mapping, Kannan-type contraction as well as Chatterjee-type contraction mappings are proved in a dislocated cone metric space over Banach algebra. Proper examples are provided to establish the validity of our claims.

In this paper, we introduce the concepts of rational type and subrational type contractive mappings. We expand and improve some fixed point theorems obtained by Alsulami et al. (Fixed Point Theory Appl., 2015, 2015: 97). Moreover, we give an example to support our results.

We discuss, extend, improve and enrich results on simulation functions established by several authors. Furthermore, by using Lemma 2.1 of Radenovic et al. [Bull. Iran. Math. Soc., 2012, 38, 625],we get much shorter and nicer proofs than the corresponding ones in the existing literature.

In the present paper, coincidence theorems of a crisp mapping and a sequence of L-fuzzy mappings have been produced under graphic contractive conditions in connection with notions of \(D_{\alpha _{L}}\) and \(d_{L}^{\infty }\) distances on the class of L-fuzzy sets. Further, we obtain some fixed point theorems for L-fuzzy set-valued mappings and pull out a variety of current results on fixed points for fuzzy mappings and multivalued mappings in the literature. As applications, we acquire coincidence points of a sequence of multivalued mappings with a self mapping and prove the existence of solution for fuzzy integral equations.

In this paper, we prove some fixed point theorems for new type generalized contractive mappings involving $${ C }$$ -class function in complex valued $$G_b$$ -metric spaces. The obtained results generalize and improve some fixed point results in the literature.

In this paper we consider, discuss and slightly complement recent fixed point results for mappings in b-metric spaces established by Sintunavarat (J Fixed Point Theory Appl 18:397–416, 2016). Thus, all our results are with shorter proofs. In addition, an application to integral equations is given to illustrate the usability of our approach.

The main aim of the current paper is the investigation of possibilities for improvements and generalizations contractive condition of Ćirić in the fuzzy metric spaces. Various versions of fuzzy contractive conditions are studied in two directions. First, motivated by recent results, more general contractive conditions in fuzzy metric spaces are achieved and secondly, quasi-contractive type of mappings are investigated in order to obtain fixed point results with a wider class of t-norms. The authors D. Rakić and T. Došenović are supported by projects MNTRRS-174009, III 44006 and PSNTR project no. 114-451-2098. Author M. De la Sen thanks the Basque Government for its support of this work through Grant IT1207-19.