Yazar "Minak, Gulhan" seçeneğine göre listele

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    Ciric Type Generalized F-contractions on Complete Metric Spaces and Fixed Point Results
    (Univ Nis, Fac Sci Math, 2014) Minak, Gulhan; Helvaci, Asuman; Altun, Ishak
    Recently, Wardowski [15] introduced the concept of F-contraction on complete metric space. This type contraction is proper generalization of ordinary contraction. In the present paper, we give some fixed point results for generalized F-contractions including Ciric type generalized F-contraction and almost F-contraction on complete metric space. Also, we give some illustrative examples.
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    An extension of Assad-Kirk's fixed point theorem for multivalued nonself mappings
    (North Univ Baia Mare, 2016) Altun, Ishak; Minak, Gulhan
    In the present paper, taking into account the recent developments on the theory of fixed point, we give some fixed point results for multivalued nonself mappings on complete metrically convex metric spaces. Our main result properly includes the famous Assad-Kirk fixed point theorem for nonself mappings. Also, we provide a nontrivial example which shows the motivation for such investigations of multivalued nonself contraction mappings.
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    Fixed Point Results for α-ψ-Contractive Mappings Including Almost Contractions and Applications
    (Hindawi Publishing Corp, 2014) Durmaz, Gonca; Minak, Gulhan; Altun, Ishak
    In the recent paper (B. Samet, C. Vetro, and P. Vetro, Fixed point theorems for alpha-psi-contractive type mappings, Nonlinear Analysis. Theory, Methods and Applications, 75 (2012), 2154-2165.), the authors introduced the concept of alpha-admissible maps on metric spaces. Using this new concept, they presented some nice fixed point results. Also, they gave an existence theorem for integral equation to show the usability of their result. Then, many authors focused on this new concept and obtained a lot of fixed point results, which are used for existence theorems. In this paper, we not only extend some of the recent results about this direction but also generalize them. Then, we give some examples to show our results are proper extensions. Furthermore, we use our results to obtain the existence and uniqueness result for a solution of fourth order two-point boundary value problem.
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    Fixed points of F-contractive type fuzzy mappings
    (Ios Press, 2017) Minak, Gulhan; Altun, Ishak; Olgun, Murat
    In this paper, taking into account the recent contractive technique, which was introduced by Wardowski [18], we present a fixed point theorem for F-contractive type fuzzy mappings over a complete metric space.
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    Fixed points of multivalued nonlinear F-contractions on complete metric spaces
    (Inst Mathematics & Informatics, 2016) Altun, Ishak; Minak, Gulhan; Olgun, Murat
    We introduce a new concept for multivalued maps, also called multivalued nonlinear F-contraction, and give a fixed point result. Our result is a proper generalization of some recent fixed point theorems including the famous theorem of Klim and Wardowski.
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    Fixed points of ordered F-contractions
    (Hacettepe Univ, Fac Sci, 2016) Durmaz, Gonca; Minak, Gulhan; Altun, Ishak
    In his recent paper, Wardowski [16] introduced the concept of F-contraction, which is a proper generalization of ordinary contraction on a complete metric space. Then, some generalizations of F-contractions including multivalued case are obtained in [2, 4, 7, 13]. In this paper, by considering both F-contractions and fixed point result on ordered metric spaces, we introduce a new concept of ordered F-contraction on ordered metric space. Then, we give a fixed point theorem for such mapping. To support our result, we give an example showing that our main theorem is applicable, but both results of Ran and Reurings [12] and Wardowski [16] are not.
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    Multivalued Almost F-contractions on Complete Metric Spaces
    (Univ Nis, Fac Sci Math, 2016) Altun, Ishak; Durmaz, Gonca; Minak, Gulhan; Romaguera, Salvador
    In the present paper, considering a new concept of multivalued almost F-contraction, we give a general class of multivalued weakly Picard operators on complete metric spaces. Also, we give some illustrative examples showing that our results are proper generalizations of some previous theorems.
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    Multivalued F-Contractions On Complete Metric Spaces
    (Yokohama Publ, 2015) Altun, Ishak; Minak, Gulhan; Dag, Hacer
    In the present paper, we introduce the concept of multivalued F-contraction mappings and give some fixed point results, which generalize some multivalued fixed point theorems including Nadler's. Also, we give an illustrating example showing that our results are proper generalization of Nadler's.
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    Multivalued Pseudo-Picard Operators and Fixed Point Results
    (Hindawi Ltd, 2013) Minak, Gulhan; Acar, Ozlem; Altun, Ishak
    We introduce the concept of multivalued pseudo-Picard (MPP) operator on ametric space. This concept is weaker than multivalued weakly Picard (MWP) operator, which is given by M. Berinde and V. Berinde (2007). Then, we give both fixed point results and examples for MPP operators. Also, we obtain some ordered fixed point results for multivalued maps as application.
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    A new approach to fixed point theorems for multivalued contractive maps
    (North Univ Baia Mare, 2015) Minak, Gulhan; Olgun, Murat; Altun, Ishak
    In the present paper, considering the Wardowski's technique we give many fixed point results for multivalued maps on complete metric space without using the Hausdorff metric. Our results are real generalization of some related fixed point theorems including the famous Feng and Liu's result in the literature. We also give some examples to both illustrate and show that our results are proper generalizations of the mentioned theorems.
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    A New Approach To Mizoguchi-Takahashi Type Fixed Point Theorems
    (Yokohama Publ, 2016) Olgun, Murat; Minak, Gulhan; Altun, Ishak
    In the present paper, we give a generalization of Mizoguchi-Takahashi's fixed point theorem, which is a partial solution of Reich's original problem concerning multivalued mappings on complete metric spaces.
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    A new approach to the Assad-Kirk fixed point theorem
    (Springer Basel Ag, 2016) Altun, Ishak; Olgun, Murat; Minak, Gulhan
    In the present paper, considering the Wardowski's technique, we give a new approach to the Assad-Kirk fixed point theorem on metrically convex metric spaces. We also provide a nontrivial example showing that our result is a proper extension of the Assad-Kirk fixed point theorem.
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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 A New Class Of Multivalued Weakly Picard Operators On Complete Metric Spaces
    (Mathematical Soc Rep China, 2015) Altun, Ishak; Olgun, Murat; Minak, Gulhan
    In the present paper, the concept of nonlinear F-contraction for multivalued mappings in metric spaces is introduced and considering the new proof technique, which was used for single valued maps by Wardowski [D. Wardowski, Fixed points of a new type of contractive mappings in complete metric spaces, Fixed Point Theory Appl. 2012, 2012: 94, 6 pp.], we demonstrate that multivalued nonlinear F-contractions of Ciric type are weakly Picard operators on complete metric spaces. Finally, we give a nontrivial example to guarantee that our result is veritable generalization of recent result of Ciric [Lj. B. Ciric, Multi-valued nonlinear contraction mappings, Nonlinear Analysis, 71 (2009), 2716-2723]. Also, we show that many fixed point results in the literature can not be applied to this example.
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    On the effect of alpha-admissibility and theta-contractivity to the existence of fixed points of multivalued mappings
    (Inst Mathematics & Informatics, 2016) Minak, Gulhan; Altun, Ishak
    In this study, we give some fixed point results for multivalued mappings using alpha-admissibility and theta-contractivity of multivalued mappings on complete metric spaces. Our results are proper generalizations of some fixed point results related to multivalued contraction. We also provide an example showing this fact. Finally, we obtain some ordered fixed point results for multivalued mappings as corollary.
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    Ordered Theta-Contractions And Some Fixed Point Results
    (Mathematical Research Press-Math Res, 2017) Minak, Gulhan; Altun, Ishak
    Recently, Jleli and Samet proved a fixed point result that is a proper generalization of the celebrated Banach contraction principle on complete metric spaces. By considering both theta-contractions and fixed point results on ordered metric spaces, we introduce a new concept of ordered theta-contractions on ordered metric spaces. Some fixed point theorems are obtained and an example is provided to support our main result.
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    Some new generalizations of Mizoguchi-Takahashi type fixed point theorem
    (Springer International Publishing Ag, 2013) Minak, Gulhan; Altun, Ishak
    In the light of the paper of Hasanzade Asl et al. (Fixed Point Theory Appl. 2012: 212, 2012, doi:10.1186/1687-1812-2012-212), we obtain a fixed point theorem for multivalued mappings on a complete metric space. Our result is a generalized version of some results in the literature, including the famous result of Mizoguchi-Takahashi (J. Math. Anal. Appl. 141:177-188, 1989). Also, we give some examples to illustrate our result.
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    A stationary point theorem for multivalued θ-contractions
    (Mathematical Research Press-Math Res, 2016) Minak, Gulhan; Altun, Ishak
    This paper is mainly devoted to a positive answer, with a new aspect, of the problem considered by Hanc, er et al. in [11] concerning multivalued version of theta - contraction which have been recently introduced by Jleli and Samet [15]. Considering delta - distance between two bounded subsets of a metric space, we provide a stationary point results for multivalued theta - contractions.