Yazar "Altun, İshak" seçeneğine göre listele
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Öğe Application of the Leray-Schauder alternative to nonlinear singular operator equations(Pergamon-Elsevier Science Ltd, 2009) Altun, İshak; Koca, KerimIn this paper, we study the problem of existence of solution of nonlinear singular integral equations of the form {w(z) = Phi(z) + T(G)F (., w (.), h (.)) (z) h(z) = Phi'(z) + Pi(G)F (., w (.), h (.)) (z), z is an element of G subset of C. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Best proximity and best periodic points for proximal nonunique contractions(Springer Basel Ag, 2021) Şahin, Hakan; Aslantaş, Mustafa; Altun, İshakTaking into account nonunique fixed point and periodic point results of Ciric (Institut Mathematique 17, 52-58, 1974) and best proximity point results in the literature, we introduce the concept of proximal nonunique contraction for nonself mappings. Then, we obtain some nonunique best proximity point theorems. Further, we describe the concept of best periodic point of nonself mappings and we present some nonunique best periodic point results. We also provide many examples to show that our new concepts are meaningful and to support our theorems. Additionally, we present a new notion for the nonself mapping H called property P-b, and then we provide some results including sufficient conditions to guarantee that H has the property P-b.Öğe A common fixed point theorem for multivalued Ćirić type mappings with new type compatibility(Ovidius Univ Press, 2009) Altun, İshakKaneko and Sessa defined the concept of compatibility for multivalued mappings with Hausdorff metric and proved a coincidence point theorem. After then, Pathak defined the concept of weak compatibility and proved a coincidence theorem. In the present work, we define a new type compatibility for multivalued mappings with Hausdorff metric. This new type compatibility is different from compatibility and weak compatibility. We give a common fixed point theorem for multivalued mappings using the new type compatibility.Öğe A common fixed point theorem for weakly compatible mappings in symmetric spaces satisfying an implicit relation(Soc Matematica Mexicana, 2007) Türkoğlu, Duran; Altun, İshakIn this paper, we prove a common fixed point theorem for weakly compatible mappings in symmetric spaces satisfying an implicit relation and a fixed point thorems under strict contractive conditions, J. Math. Anal. Appl. 270 (2002) 181-188]. Our theorem generalizes Theorem 1 of [A. Aliouche, A common fixed point theorem for weakly compatible mappings in symmetric spaces satisfying a contractive condition of integral type Theorem 2.2 of [M. Aamri, D. El Moutawakil, Common fixed points under contractive conditions in symmetric spaces, Appl. Math. E-Notes 3 (2003) 156-162] and Theorem 2 of [M. Aamri, D. El Moutawakil, Some new common fixed point thorems under strict contractive conditions, J. Math. Anal. Appl. 270 (2002) 181-188].Öğe Common fixed points of Ciric-type contractions on partial metric spaces(Kossuth Lajos Tudomanyegyetem, 2013) Abbas, Mujahid; Altun, İshak; Romaguera, SalvadorWe obtain a common fixed point theorem of Boyd-Wong type for four mappings satisfying a Ciric-type contraction on a complete partial metric space. Our result generalizes and unifies, among others, the very recent results of L. CIRIC, B. SAMET, H. AYDI and C. VETRO [Common fixed points of generalized contractions on partial metric spaces and an application, Appl. Math. Comput., 218 (2011), 2398-2406], S. ROMAGUERA [Fixed point theorems for generalized contractions on partial metric spaces, Topology Appl., 159 (2012), 194-199], T. ABDELJAWAD, E. KARAPINAR and K. TAS [Existence and uniqueness of a common fixed point on partial metric spaces, Appl. Math. Lett. 24 (2011), 1900-1904], and D. ILIC, V. PAVLOVIC and V. RAKOCEVIC [Some new extensions of Banach's contraction principle to partial metric space, Appl. Math. Lett. 24 (2011), 1326-1330].Öğe A fixed fuzzy point for fuzzy mappings in complete metric spaces(Univ Osijek, Dept Mathematics, 2008) Sedghi, Shaban; Shobe, Nabi; Altun, İshakIn this paper we prove a fixed point theorem for fuzzy mappings over a complete metric space.Öğe A Fixed Point Theorem for Multivalued Mappings with δ-Distance(Hindawi Publishing Corporation, 2014) Acar, Özlem; Altun, İshakWe mainly study fixed point theorem for multivalued mappings with delta-distance using Wardowski's technique on complete metric space. Let (X, d) be a metric space and let B(X) be a family of all nonempty bounded subsets of X. Define delta : B(X) x B(X) -> R by delta(A, B) = sup {d(a, b): a is an element of A, b is an element of B}. Considering delta-distance, it is proved that if (X, d) is a complete metric space and T : X -> B(X) is a multivalued certain contraction, then T has a fixed point.Öğe A Fixed Point Theorem for New Type Contractions on Weak Partial Metric Spaces(Springer Singapore Pte Ltd, 2015) Acar, Özlem; Altun, İshak; Durmaz, GoncaRecently, Karapinar and Romaguera (Filomat 27: 1305-1314, 2013) have introduced a new type contraction on partial metric spaces, and they have obtained a nonunique fixed point result. Then Romaguera (Math. Sci. Appl. E-Notes 1: 1-8, 2013) used this contraction to obtain some multivalued fixed point results on partial metric spaces. In the present work, we give a fixed point result on weak partial metric spaces using this new idea.Öğe Fixed point theorem for sequences of maps(Walter de Gruyter GmbH, 2005) Turkoglu, D.; Altun, İshak; Fisher, B.In this paper, we prove a common fixed point theorem for sequences of maps under the condition of compatible mappings on complete metric space. We extend and generalize several fixed point theorems on complete metric space. © 2005 Warsaw University. All rights reserved.Öğe Fixed Point Theorems for Generalized Weakly Contractive Condition in Ordered Metric Spaces(Springer International Publishing Ag, 2011) Nashine, Hemant Kumar; Altun, İshakFixed point results with the concept of generalized weakly contractive conditions in complete ordered metric spaces are derived. These results generalize the existing fixed point results in the literature.Öğe Fixed Point Theorems for Monotone Mappings on Partial Metric Spaces(Springer International Publishing Ag, 2011) Altun, İshak; Erduran, AliMatthews (1994) introduced a new distance p on a nonempty set X, which is called partial metric. If (X,p) is a partial metric space, then p(x,x) may not be zero for x is an element of X. In the present paper, we give some fixed point results on these interesting spaces.Öğe Fixed point theorems for weak contractions in the sense of Berinde on partial metric spaces(Elsevier Science Bv, 2012) Altun, İshak; Acar, ÖzlemIn this paper, we introduce the notion of (delta . L) weak contraction and (phi . L) weak contraction in the sense of Berinde in partial metric space. Then we give some fixed point results in partial metric space using these new concepts. (C) 2012 Elsevier B.V. All rights reserved.Öğe Fixed Point Theorems on Complete Quasi Metric Spaces Via C-class and A-Class Functions(UNIV MARAGHEH, 2020) Yalçın, M. Tugba; Şimşek, Hakan; Altun, İshakIn this paper, we present some fixed point theorems for single valued mappings on K-complete, M-complete and Symth complete quasi metric spaces. Here, for contractive condition, we consider some altering distance functions together with functions belonging to C-class and A-class. At the same time, we will consider two different type M functions in contractive conditions because the quasi metric does not provide the symmetry property. Finally, we show that our main results includes many fixed point theorems presented on both complete metric and complete quasi metric spaces in the literature. We also provide an illustrative example to show importance of our results.Öğe Fixed points of weakly compatible maps satisfying a general contractive condition of integral type(Springer, 2007) Altun, İshak; Türkoğlu, Duran; Rhoades, Billy E.We prove a fixed point theorem for weakly compatible maps satisfying a general contractive condition of integral type. Copyright (C) 2007.Öğe Generalized contractions on partial metric spaces(Elsevier Science Bv, 2010) Altun, İshak; Sola, Ferhan; Şimşek, HakanIn the present paper, we give some fixed point theorems for generalized contractive type mappings on partial metric space. Also, a homotopy result is given. (C) 2010 Elsevier B.V. All rights reserved.Öğe Ordered cone metric spaces and fixed point results(Pergamon-Elsevier Science Ltd, 2010) Altun, İshak; Rakocevic, VladimirIn this paper, we introduce a partial order on a cone metric space and prove a Caristi-type theorem. Furthermore, we prove fixed point theorems for single-valued nondecreasing and weakly increasing mappings, and multi-valued mappings on an ordered cone metric space. (C) 2010 Elsevier Ltd. All rights reserved.Öğe A related fixed point theorem for maps in two S-complete Hausdorff uniform spaces(Ios Press, 2014) Shobkolaei, Nabi; Sedghi, Shaban; Roshan, Jamal R.; Altun, İshakThe purpose of this paper is to prove a related fixed point in S-complete Hausdorff uniform space. For this we use the concept of E-distance, which is introduced by Aamri and El-Moutawakil [1, 2], in uniform space and some metric versions of related fixed point theorems.Öğe Some coincidence point results in ordered b-metric spaces and applications in a system of integral equations(Elsevier Science Inc, 2014) Roshan, J. R.; Parvaneh, V.; Altun, İshakThe aim of this paper is to present some coincidence point results for four mappings satisfying generalized (psi, phi)-weakly contractive condition in the framework of ordered b-metric spaces. An example and an application are also provided to support our results. (C) 2013 Elsevier Inc. All rights reserved.Öğe Some Fixed Point Results for ?-Admissible Mappings on Quasi Metric Space Via ?-Contractions(Murat TOSUN, 2024) Güngör, Gonca Durmaz; Altun, İshakBy implying ?-admissible mapping, this study expands and investigates generalized contraction mappings in quasi-metric spaces, aiming to establish the existence of fixed points. Moreover, we show that the main outcomes of the paper encompass several previously reported results in the literature. © MSAEN.Öğe Some fixed point theorems for weakly compatible mappings satisfying an implicit relation(Mathematical Soc Rep China, 2009) Altun, İshak; Türkoğlu, DuranIn this paper, we prove a common fixed point theorem for weakly compatible mappings satisfying an implicit relation. Our theorem generalizes many fixed point theorems.
