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Now showing 1 - 6 of 6
  • Editorial
    Advances on Multivalued Operators and Related Fixed Point Problems
    (Hindawi Publishing Corporation, 2014) Chen, Chi-Ming; Karapinar, Erdal; Du, Wei-Shih; Aydi, Hassen; Romaguera, Salvador
    [No Abstract Available]
  • Article
    Citation - WoS: 11
    Citation - Scopus: 15
    Fixed points for cyclic orbital generalized contractions on complete metric spaces
    (de Gruyter Open Ltd, 2013) Karapinar, Erdal; Romaguera, Salvador; Tas, Kenan
    We prove a fixed point theorem for cyclic orbital generalized contractions on complete metric spaces from which we deduce, among other results, generalized cyclic versions of the celebrated Boyd and Wong fixed point theorem, and Matkowski fixed point theorem. This is done by adapting to the cyclic framework a condition of Meir-Keeler type discussed in [Jachymski J., Equivalent conditions and the Meir-Keeler type theorems, J. Math. Anal. Appl., 1995, 194(1), 293-303]. Our results generalize some theorems of Kirk, Srinavasan and Veeramani, and of Karpagam and Agrawal.
  • Article
    Citation - WoS: 15
    Contractive Multivalued Maps in Terms of q-functions on Complete Quasimetric Spaces
    (Springer international Publishing Ag, 2014) Karapinar, Erdal; Romaguera, Salvador; Tirado, Pedro
    In this paper we prove the existence of a fixed point for multivalued maps satisfying a contraction condition in terms of Q-functions, and via Bianchini-Grandolfi gauge functions, for complete T-0-quasipseudometric spaces. Our results extend, improve, and generalize some recent results in the literature. We present some examples to validate and illustrate our results.
  • Article
    A Note on the Structure of Interpolative Metric Spaces
    (Univ Nis, Fac Sci Math, 2025) Karapinar, Erdal; Romaguera, Salvador
    In 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: 27
    Citation - Scopus: 29
    On the Weak Form of Ekeland's Variational Principle in Quasi-Metric Spaces
    (Elsevier, 2015) Karapinar, Erdal; Romaguera, Salvador
    We show that a quasi-metric space is right K-sequentially complete if and only if it satisfies the property of the weak form of Eke land's Variational Principle. This result solves a question raised by S. Cobzas (2011) [3]. (C) 2015 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 31
    Citation - Scopus: 36
    Nonunique Fixed Point Theorems in Partial Metric Spaces
    (Univ Nis, Fac Sci Math, 2013) Karapinar, Erdal; Romaguera, Salvador
    In this paper we prove the existence of fixed points of certain self-maps in the context of partial metric spaces. In fact, the fixed point theorems presented here can be considered as a continuation, in part, of the works of L. B. Ciric on the existence of fixed points but not uniqueness in the realm of metric spaces. Our results generalize, enrich and improve earlier results on the topic in the literature.