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Ovidiu Popescu

Publications and source records attributed to Ovidiu Popescu.

6 recordsLinked to original sources

On Significant Pointwise Contractions and Annular Contractions

In the current paper, we introduce the class of \textit{significant pointwise contractions}. This family of mappings extends the classical Banach contractions and also contains nonexpansive mappings. We prove that in a complete metric space every significant pointwise contraction admits a fixed point that can be approximated through Picard iterations. We provide examples showing that the newly introduced class differs from the class of piecewise contractions and is not contained in it. Moreover, we point out that significant pointwise contractions are continuous and may possess multiple fixed points. We further introduce the class of \textit{significant pointwise shrinkings}, which generalizes the class of shrinkings, and prove that any such mapping has a fixed point in a compact metric space. Moreover, we define the class of \textit{annular pointwise contractions}, which includes Banach contractions but is distinct from the class of Suzuki mappings. Finally, we obtain a fixed point theorem for annular pointwise contractions and present an additional condition ensuring the existence of fixed points.

math.FA

On fixed point results in metric spaces for large triangle-perimeter contractions

In this paper we introduce a corrected extension of Burton's theory of large contractions in the context of triangle-perimeter contractions introduced by Petrov. Combining these two lines of research, we prove a fixed point result for large triangle-perimeter contractions with an auxiliary assumption, which is of utmost importance. Firstly, we give a counterexample to the main result related to large triangle-perimeter contractions that currently exists in literature. Then, we prove that given an additional condition, a fixed point result for large triangle-perimeter contractions holds. Lastly, we illustrate with an example that this new framework is strictly broader than Burton's and Petrov's theory.

math.DS

Fixed points for three point generalized orbital triangular contractions

In this paper we introduce and study new classes of mappings in metric spaces. The main class of mappings is called generalized orbital triangular contractions and it generalizes some existing results (such as Banach contractions, mappings contracting perimeters of triangles). We prove that these contractions are not necessarily continuous and have a unique fixed point under certain conditions. Moreover, we extend our class to generalized orbital triangular Kannan contractions and generalized orbital triangular Chatterjea contractions.

math.GN

Fixed point theorem for generalized Chatterjea type mappings

We introduce a new type of mappings in metric space which are three-point analogue of the well-known Chatterjea type mappings, and call them generalized Chatterjea type mappings. It is shown that such mappings can be discontinuous as is the case of Chatterjea type mappings and this new class includes the class of Chatterjea type mappings. The fixed point theorem for generalized Chatterjea type mappings is proven.

math.MG

Mappings contracting triangles

The aim of the current paper is to introduce a new class of contractive mappings, which are contracting (a feature of) triangles. We prove that maps contracting triangles are continuous and give the fixed point result for such mappings. We emphasize that our main theorem encompasses many functions, with significant applicability, for which the result holds, thereby representing a notable advancement in this research domain.

math.GN

Some remarks on expansive mappings in metric spaces

The aim of this paper is to generalize the results on expansive mappings of Yesilkaya and Aydin from \cite{Yesilkaya}. We give some fixed point results for q-expansive mappings in metric spaces and prove some fixed point theorems for this class of mappings. Finally, we present some examples to support the new results.

math.GN