Browsing by Author "Romaguera, Salvador"

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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; Mathematics
[No Abstract Available]
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; Mathematics
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.
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; Mathematics
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.
Citation - WoS: 30
Citation - Scopus: 36
Nonunique Fixed Point Theorems in Partial Metric Spaces
(Univ Nis, Fac Sci Math, 2013) Karapinar, Erdal; Romaguera, Salvador; Mathematics
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.
Citation - WoS: 26
Citation - Scopus: 28
On the Weak Form of Ekeland's Variational Principle in Quasi-Metric Spaces
(Elsevier, 2015) Karapinar, Erdal; Romaguera, Salvador; Mathematics
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.