Yazar "Romaguera, Salvador" seçeneğine göre listele

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    Caristi's Type Mappings On Complete Partial Metric Spaces
    (House Book Science-Casa Cartii Stiinta, 2013) Acar, Ozlem; Altun, Ishak; Romaguera, Salvador
    We introduce a new type of Caristi's mapping on partial metric spaces and show that a partial metric space is complete if and only if every Caristi mapping has a fixed point. From this result we deduce a characterization of bicomplete weightable quasi-metric spaces. Several illustrative examples are given.
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    Characterizations of partial metric completeness in terms of weakly contractive mappings having fixed point
    (Univ Belgrade, Fac Electrical Engineering, 2012) Altun, Ishak; Romaguera, Salvador
    We characterize both complete and 0-complete partial metric spaces in terms of weakly contractive mappings having a fixed point. Our results extend a well-known characterization of metric completeness due to SUZUKI and TAKAHASHI to the partial metric framework.
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    Common fixed points of Ciric-type contractions on partial metric spaces
    (Kossuth Lajos Tudomanyegyetem, 2013) Abbas, Mujahid; Altun, İshak; Romaguera, Salvador
    We 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].
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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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    Recent developments about multivalued weakly Picard operators
    (Belgian Mathematical Soc Triomphe, 2015) Minak, Guelhan; Altun, Ishak; Romaguera, Salvador
    In the present paper, considering a recent technique, which is used by Wardowski [24] for fixed points of single-valued mappings, we give a new and general class of multivalued weakly Picard operators on complete metric spaces and show that the class of multivalued almost contractions (both linear and nonlinear cases in the sense of Berinde and Berinde [9]) is a proper subset of this new class. We also give a nontrivial example showing this fact.