scholarly journals A Characterization of the discontinuity point set of strongly separately continuous functions on products

2016 ◽  
Vol 66 (6) ◽  
Author(s):  
Olena Karlova ◽  
Volodymyr Mykhaylyuk

AbstractWe study properties of strongly separately continuous mappings defined on subsets of products of topological spaces equipped with the topology of pointwise convergence. In particular, we give a necessary and sufficient condition for a strongly separately continuous mapping to be continuous on a product of an arbitrary family of topological spaces. Moreover, we characterize the discontinuity point set of strongly separately continuous function defined on a subset of countable product of finite-dimensional normed spaces.

Author(s):  
Majid Mirmiran ◽  
Binesh Naderi

‎A necessary and sufficient condition in terms of lower cut sets ‎are given for the insertion of a contra-continuous function ‎between two comparable real-valued functions on such topological ‎spaces that kernel of sets are open‎. 


1998 ◽  
Vol 10 (04) ◽  
pp. 439-466 ◽  
Author(s):  
Elisa Ercolessi ◽  
Giovanni Landi ◽  
Paulo Teotonio-Sobrinho

Recently a new kind of approximation to continuum topological spaces has been introduced, the approximating spaces being partially ordered sets (posets) with a finite or at most a countable number of points. The partial order endows a poset with a nontrivial non-Hausdorff topology. Their ability to reproduce important topological information of the continuum has been the main motivation for their use in quantum physics. Posets are truly noncommutative spaces, or noncommutative lattices, since they can be realized as structure spaces of noncommutative C*-algebras. These noncommutative algebras play the same rôle as the algebra of continuous functions [Formula: see text] on a Hausdorff topological space M and can be thought of as algebras of operator valued functions on posets. In this article, we will review some mathematical results that establish a duality between finite posets and a certain class of C*-algebras. We will see that the algebras in question are all postliminal approximately finite dimensional (AF) algebras.


2007 ◽  
Vol 72 (4) ◽  
pp. 1379-1384 ◽  
Author(s):  
Douglas Bridges ◽  
Hannes Diener

AbstractWe prove constructively that, in order to derive the uniform continuity theorem for pointwise continuous mappings from a compact metric space into a metric space, it is necessary and sufficient to prove any of a number of equivalent conditions, such as that every pointwise continuous mapping of [0, 1] into ℝ is bounded. The proofs are analytic, making no use of, for example, fan-theoretic ideas.


Author(s):  
Alpa Singh Rajput ◽  
S. S. Thakur ◽  
Om Prakash Dubey

Purpose: In the present paper the concept of soft almost β-continuous mappings and soft almost β-open mappings in soft topological spaces have been introduced and studied. Methodology: This notion is weaker than both soft almost pre-continuous mappings, soft almost semi-continuous mapping. The diagrams of implication among these soft classes of soft mappings have been established. Main Findings: We extend the concept of almost β-continuous mappings and almost β-open mappings in soft topology. Implications: Mapping is an important and major area of topology and it can give many relationships between other scientific areas and mathematical models. This notion captures the idea of hanging-togetherness of image elements in an object by assigning strength of connectedness to every possible path between every possible pair of image elements. It is an important tool for the designing of algorithms for image segmentation. The novelty of Study: Hope that the concepts and results established in this paper will help the researcher to enhance and promote the further study on soft topology to carry out a general framework for the development of information systems.


2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Ting Yang ◽  
Ahmed Mostafa Khalil

In this article, we will define the new notions (e.g., b − θ -neighborhood system of point, b − θ -closure (interior) of a set, and b − θ -closed (open) set) based on fuzzy logic (i.e., fuzzifying topology). Then, we will explain the interesting properties of the above five notions in detail. Several basic results (for instance, Definition 7, Theorem 3 (iii), (v), and (vi), Theorem 5, Theorem 9, and Theorem 4.6) in classical topology are generalized in fuzzy logic. In addition to, we will show that every fuzzifying b − θ -closed set is fuzzifying γ -closed set (by Theorem 3 (vi)). Further, we will study the notion of fuzzifying b − θ -derived set and fuzzifying b − θ -boundary set and discuss several of their fundamental basic relations and properties. Also, we will present a new type of fuzzifying strongly b − θ -continuous mapping between two fuzzifying topological spaces. Finally, several characterizations of fuzzifying strongly b − θ -continuous mapping, fuzzifying strongly b − θ -irresolute mapping, and fuzzifying weakly b − θ -irresolute mapping along with different conditions for their existence are obtained.


2007 ◽  
Vol 75 (3) ◽  
pp. 373-379 ◽  
Author(s):  
Oleksandr V. Maslyuchenko

It is proved that a subsetEof a hereditarily normal topological spaceXis a discontinuity point set of some quasi-continuous functionf:X→ ℝ if and only ifEis a countable union of setsEn=Ān⋂Bdash abovenwhereĀn⋂Bn=An⋂Bdash aboven= φ


2005 ◽  
Vol 2005 (1) ◽  
pp. 19-32 ◽  
Author(s):  
A. A. Ramadan ◽  
S. E. Abbas ◽  
A. A. Abd El-Latif

We introduce fuzzy almost continuous mapping, fuzzy weakly continuous mapping, fuzzy compactness, fuzzy almost compactness, and fuzzy near compactness in intuitionistic fuzzy topological space in view of the definition of Šostak, and study some of their properties. Also, we investigate the behavior of fuzzy compactness under several types of fuzzy continuous mappings.


We introduce and study several interesting properties of fuzzy almost generalized e -continuous mappings in smooth topological spaces with counter examples. We also introduce fuzzy r - 1 2 fT e -space, r -fuzzy ge -space, r -fuzzy regular ge -space and r -fuzzy generalized e -compact space. It is seen that a fuzzy almost generalized e -continuous mapping, between a fuzzy r - 1 2 fT e -space and a fuzzy topological space, becomes fuzzy almost continuous mapping. Index Terms: fage -continuous, r - fge -space, r - fge -regular space, r - 1 2 fT e -space.


2019 ◽  
Vol 20 (1) ◽  
pp. 75
Author(s):  
Yaroslav I. Grushka

<p>Let T = (<strong>T</strong>, ≤) and T<sub>1</sub>= (<strong>T</strong><sub>1</sub> , ≤<sub>1</sub>) be linearly ordered sets and X be a topological space.  The main result of the paper is the following: If function ƒ(t,x) : <strong>T</strong> × X → <strong>T</strong><sub>1 </sub>is continuous in each  variable (“t” and  “x”)  separately  and  function ƒ<sub>x</sub>(t)  = ƒ(t,x) is  monotonous  on <strong>T</strong> for  every x ∈ X,  then ƒ is  continuous  mapping  from<strong> T</strong> × X to <strong>T</strong><sub>1</sub>,  where <strong>T</strong> and <strong>T</strong><sub>1</sub> are  considered  as  topological  spaces  under  the order topology and <strong>T</strong> × X is considered as topological space under the Tychonoff topology on the Cartesian  product of topological spaces <strong>T</strong> and X.</p>


Author(s):  
Ch. Konstadilaki-Savvapoulou ◽  
D. Janković

A strong form of continuity of functions between topological spaces is introduced and studied. It is shown that in many known results, especially closed graph theorems, functions under consideration areR-continuous. Several results in the literature concerning strong continuity properties are generalized and/or improved.


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