Results 21 to 30 of about 61 (61)

Some Fixed Point Theorems for Multi-Valued Contractions in Quasi-Metric Spaces [PDF]

, 2012
In this paper, we study fixed point theorems in quasi-metric spaces and obtain some result in it. Also, the paper contains generalized fixed point theorems of L. B.
Seiedeh Fereshteh Hashemi
core  

Echeloned Spaces

Forum of Mathematics, Sigma
We introduce the notion of echeloned spaces – an order-theoretic abstraction of metric spaces. The first step is to characterize metrizable echeloned spaces. It turns out that morphisms between metrizable echeloned spaces are uniformly continuous or have
Maxime Gheysens, Bojana Pavlica, Christian Pech, Maja Pech, Friedrich Martin Schneider   +4 more
doaj   +1 more source

ℐ-sn-metrizable spaces and the images of semi-metric spaces

Open Mathematics
The theory of generalized metric spaces is an active topic in general topology. In this article, we utilize the concepts of ideal convergence and networks to discuss the metrization problem and the mutual classification problem between spaces and ...
Zhou Xiangeng, Liu Fang, Liu Li, Lin Shou   +3 more
doaj   +1 more source

Characterizations of Urysohn universal ultrametric spaces

Analysis and Geometry in Metric Spaces
In this article, using the existence of infinite equidistant subsets of closed balls, we first characterize the injectivity of ultrametric spaces for finite ultrametric spaces. This method also gives characterizations of the Urysohn universal ultrametric
Ishiki Yoshito
doaj   +1 more source

On the Borel complexity and the complete metrizability of spaces of metrics

Analysis and Geometry in Metric Spaces
Given a metrizable space XX, let AM(X)AM\left(X) be the space of continuous bounded admissible metrics on XX, which is endowed with the sup-metric. In this article, we shall investigate the Borel complexity and the complete metrizability of AM(X)AM\left ...
Koshino Katsuhisa
doaj   +1 more source

New common fixed point results in digital metric space

Demonstratio Mathematica
In this paper, we develop a new common fixed-point theorem tailored specifically to digital metric spaces, where the discrete nature of pixel grids demands specialized distance and contraction concepts.
Özkapu Aybala Sevde, Acar Özlem
doaj   +1 more source

Geometric fuzzification

, 2004
unavailable at this time... Mathematics Subject Classification (2000): 03E72, 52A01, 54E35, 53C70, 14M15 Quaestiones Mathematicae 25 (2002), 147 ...
Lubczonok, G, Remsing, C.C
core  

Preimages of ultrafilters need not extend to ultrafilters in ZF

, 2020
We construct a permutation model M with a set of atoms A and an onto function f : A → ω such that A and ω have free ultrafilters but that for each free ultrafilter on ω its preimage under f does not extend to an ultrafilter on A.
Paul Howard, Kyriakos Keremedis, Horst Herrlich   +2 more
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Striking differences between ZF and ZF+ weak choice in view of metric spaces

, 2004
unavailable at this time...Mathematics Subject Classification (2000): 03E25, 54A25, 54C05, 54C05, 54C25, 54D20, 54E35 Quaestiones Mathematicae 25 (2002), 405 ...
Keremedis, Kyriakos, Herrlich, Horst, Tachtsis, Eletherios   +2 more
core  

Some Results on Fixed Point Theorems of Weak Cyclic ϕ-Contractions in Parametric b-metric Spaces

In this paper, we introduce the notions of cyclic ϕ-contractions and quasi-like weak cyclic ϕcontractions in parametric b-metric spaces, where ϕ is a comparison-type function.
P.G. Golhare
core   +1 more source