Erdal Karapinar

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The notion of coupled fixed point is introduced by Gnana-Bhaskar and Lakshmikantham. Very recently, the concept of tripled fixed point was introduced by Berinde and Borcut. In this manuscript, a quadruple fixed point is considered and some new related fixed point theorems are obtained. We also give some examples to illustrate our results. © 2012 Elsevier(More)
Given A and B two subsets of a metric space, a mapping T : A∪B → A∪B is said to be cyclic if T (A) ⊆ B and T (B) ⊆ A. It is known that, if A and B are nonempty and complete and the cyclic map verifies for some k ∈ (0, 1) that d(Tx, Ty) ≤ kd(x, y) ∀ x ∈ A and y ∈ B, then A∩B 6= ∅ and the mapping T has a unique fixed point. A generalization of this situation(More)
Cone-valued lower semicontinuous maps are used to generalize Cristi-Kirik’s fixed point theorem to Cone metric spaces. The cone under consideration is assumed to be strongly minihedral and normal. First we prove such a type of fixed point theorem in compact cone metric spaces and then generalize to complete cone metric spaces. Some more general results are(More)
We obtain some fixed point theorems for two pairs of hybrid mappings using hybrid tangential property and quadratic type contractive condition. Our results generalize some results by Babu and Alemayehu and those contained therein. In the sequel, we introduce a new notion to generalize occasionally weak compatibility. Moreover, two concrete examples are(More)