Yazar "Hancer, Hatice Aslan" seçeneğine göre listele

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    Almost Picard Operators
    (Amer Inst Physics, 2019) Altun, Ishak; Hancer, Hatice Aslan
    The concept of Picard operator is one of the most important concept of fixed point theory. As known, a self mapping T of a metric space X is called Picard operator (PO) if it has unique fixed point and every Picard iteration sequence converges to this fixed point. There are some weaker forms of PO in the literature as weakly Picard operator (WPO) and pseudo Picard operator (PPO). In this study, we present a new kind of PO as almost Picard operator (APO) and we show the differences from the others. Then we show that every continuous P-contractive self mapping of a compact metric space is APO. Also we present some open problems.
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    Fixed point results for P-contractions via w-distance
    (SINUS Association, 2023) Altun, Ishak; Hancer, Hatice Aslan; Başar, Ümran
    In the present paper, we define the P w-contraction by considering the inequality called P contraction in metric space together with the w-distance. We then present fixed point theorems for both singlevalued and multivalued P w-contractions. We also support our results with suitable examples. © 2023, SINUS Association. All rights reserved.
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    Fixed point results for single valued and set valued P-contractions and application to second order boundary value problems
    (NORTH UNIV BAIA MARE, 2020) Altun, Ishak; Hancer, Hatice Aslan; Erduran, Ali
    In this paper, by considering the concept of set-valued nonlinear P-contraction which is newly introduced, we present some new fixed point theorems for set-valued mappings on complete metric space. Then by considering a single-valued case we provide an existence and uniqueness result for a kind of second order two point boundary value problem.
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    Nonself P-contractions on convex metric spaces and their fixed points
    (Springernature, 2022) Altun, Ishak; Hancer, Hatice Aslan; Erduran, Ali
    In this paper, we present some new fixed point results for single-valued nonself mappings from a closed subset K of a metrically convex metric space M into M. Here we consider recent approaches for contractive condition named as P-contraction. We provide some examples to support our results. Then by taking into account the compactness of the subset K, we consider a strict version of P-contraction without contractive constant and so we present a new result. Finally, we give the nonself version of the famous Edelstein fixed point theorem as corollary.
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    On A Broad Category Of Multivalued Weakly Picard Operators
    (House Book Science-Casa Cartii Stiinta, 2017) Hancer, Hatice Aslan; Minak, Gulhan; Altun, Ishak
    In the present paper, considering a recent technique which is used by Jleli and Samet [10] for fixed points of single-valued maps, we introduce a new concept of multivalued theta-contractions on metric spaces and prove that some of such mappings are multivalued weakly Picard operators on complete metric space. Finally, we give a nontrivial example to show that the class of multivalued theta-contractions is more general than multivalued contractions in the sense of Nadler [14] on complete metric spaces.
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    ON MULTIVALUED P-CONTRACTIVE MAPPINGS THAT BELONGS TO CLASS OF WEAKLY PICARD OPERATORS
    (House Book Science-Casa Cartii Stiinta, 2021) Hancer, Hatice Aslan
    In the present paper, by introducing the P-contractivity of a multivalued mapping, we give a new class of multivalued weakly Picard operators on complete metric spaces and show that the class of multivalued contractions is a proper subset of this new class. We also give a nontrivial example showing this fact.
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    Some new extensions of Darbo's fixed point theorem with application
    (Univ Nis, Fac Sci Math, 2024) Gencturk, Lker; Hancer, Hatice Aslan; Altun, Ishak
    We present some new extensions of Darbo's fixed-point theorem with a different aspect than those available in the literature by introducing the concept of (k, L)-set contraction. The concept of (k, L)-set contraction is interesting since there is no restriction for the constant L. We also present the nonlinear Leray-Schauder type alternative for one of our results. Finally, to demonstrate the applicability, we utilize theoretical results to provide the existence of solution of an integral equation.
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    Some new types multivalued F-contractions on quasi metric spaces and their fixed points
    (North Univ Baia Mare, 2019) Hancer, Hatice Aslan; Olgun, Murat; Altun, Ishak
    In this paper we present two new results for the existence of fixed points of multivalued mappings with closed values on quasi metric space. First we introduce the multivalued F-d-contraction on quasi metric space (X, d) and give a fixed point result related to this concept. Then taking into account the Q-function on a quasi metric space, we establish a Q-function version of this concept as multivalued F-q-contraction and hence we present a fixed point result to see the effect of Q-function to existence of fixed point of multivalued mappings on quasi metric space.