scholarly journals On rings of real valued clopen continuous functions

2018 ◽  
Vol 19 (2) ◽  
pp. 203
Author(s):  
Susan Afrooz ◽  
Fariborz Azarpanah ◽  
Masoomeh Etebar
Keyword(s):  
Topological Space ◽  
Maximal Ideal ◽  
Quotient Space ◽  
Inverse Image ◽  
Continuous Functions ◽  
Discrete Space ◽  
Strong Continuity ◽  
Open Set ◽  
Maximal Ideals ◽  
Essential Ideal

<p>Among variant kinds of strong continuity in the literature, the clopen continuity or cl-supercontinuity (i.e., inverse image of every open set is a union of clopen sets) is considered in this paper.  We investigate and study the ring C<sub>s</sub>(X) of all real valued clopen continuous functions on a topological space X.  It is shown that every ƒ ∈ C<sub>s</sub>(X) is constant on each quasi-component in X and using this fact we show that C<sub>s</sub>(X) ≅ C(Y), where Y is a zero-dimensional s-quotient space of X.  Whenever X is locally connected, we observe  that C<sub>s</sub>(X) ≅ C(Y),  where Y is a discrete space.  Maximal ideals of C<sub>s</sub>(X) are characterized in terms of quasi-components in X and it turns out that X  is mildly compact(every clopen cover has a finite subcover) if and only if every maximal ideal  of C<sub>s</sub>(X)is  fixed. It is shown that the socle of C<sub>s</sub>(X) is  an essential ideal if and only if the union of all open quasi-components in X is s-dense.  Finally the counterparts of some familiar spaces, such as P<sub>s</sub>-spaces, almost P<sub>s</sub>-spaces, s-basically and s-extremally disconnected spaces  are  defined  and  some  algebraic  characterizations  of  them  are given via the ring C<sub>s</sub>(X).</p>

scholarly journals Lebesgue Measurability of Separately Continuous Functions and Separability

2007 ◽  
Vol 2007 ◽  
pp. 1-4
Author(s):  
V. V. Mykhaylyuk
Keyword(s):  
Topological Space ◽  
Chain Condition ◽  
Continuous Functions ◽  
Negative Answer ◽  
Regular Space ◽  
Property A ◽  
Completely Regular ◽  
Open Set ◽  
Countable Chain Condition ◽  
Countable Chain

A connection between the separability and the countable chain condition of spaces withL-property (a topological spaceXhasL-property if for every topological spaceY, separately continuous functionf:X×Y→ℝand open setI⊆ℝ,the setf−1(I)is anFσ-set) is studied. We show that every completely regular Baire space with theL-property and the countable chain condition is separable and constructs a nonseparable completely regular space with theL-property and the countable chain condition. This gives a negative answer to a question of M. Burke.

scholarly journals Characterizations of Ideals in IntermediateC-RingsA(X)via theA-Compactifications ofX

2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
Joshua Sack ◽  
Saleem Watson
Keyword(s):  
Topological Space ◽  
Continuous Functions ◽  
Completely Regular ◽  
Intermediate Ring ◽  
Maximal Ideals ◽  
Kolmogorov Theorem

LetXbe a completely regular topological space. An intermediate ring is a ringA(X)of continuous functions satisfyingC*(X)⊆A(X)⊆C(X). In Redlin and Watson (1987) and in Panman et al. (2012), correspondences𝒵AandℨAare defined between ideals inA(X)andz-filters onX, and it is shown that these extend the well-known correspondences studied separately forC∗(X)andC(X), respectively, to any intermediate ring. Moreover, the inverse map𝒵A←sets up a one-one correspondence between the maximal ideals ofA(X)and thez-ultrafilters onX. In this paper, we define a function𝔎Athat, in the case thatA(X)is aC-ring, describesℨAin terms of extensions of functions to realcompactifications ofX. For such rings, we show thatℨA←mapsz-filters to ideals. We also give a characterization of the maximal ideals inA(X)that generalize the Gelfand-Kolmogorov theorem fromC(X)toA(X).

scholarly journals Fine Fuzzy sp Closed Sets in Fine Fuzzy Topological Spaces

2020 ◽  
Vol 9 (3) ◽  
pp. 1306-1313
Keyword(s):  
Continuous Function ◽  
Topological Space ◽  
Inverse Image ◽  
Continuous Functions ◽  
Topological Spaces ◽  
The Novel ◽  
Closed Set ◽  
Closed Sets ◽  
Fuzzy Topological Space ◽  
Fuzzy Topological Spaces

The main view of this article is the extended version of the fine topological space to the novel kind of space say fine fuzzy topological space which is developed by the notion called collection of quasi coincident of fuzzy sets. In this connection, fine fuzzy closed sets are introduced and studied some features on it. Further, the relationship between fine fuzzy closed sets with certain types of fine fuzzy closed sets are investigated and their converses need not be true are elucidated with necessary examples. Fine fuzzy continuous function is defined as the inverse image of fine fuzzy closed set is fine fuzzy closed and its interrelations with other types of fine fuzzy continuous functions are obtained. The reverse implication need not be true is proven with examples. Finally, the applications of fine fuzzy continuous function are explained by using the composition.

scholarly journals Characterizations of some near-continuous functions and near-open functions

1986 ◽  
Vol 9 (4) ◽  
pp. 715-720 ◽  
Author(s):  
C. W. Baker
Keyword(s):  
Topological Space ◽  
Continuous Functions ◽  
Open Set ◽  
Weakly Continuous ◽  
Almost Open ◽  
Open Maps

A subsetNof a topological space is defined to be aθ-neighborhood ofxif there exists an open setUsuch thatx∈U⫅C1   U⫅N. This concept is used to characterize the following types of functions: weakly continuous,θ-continuous, stronglyθ-continuous, almost stronglyθ-continuous, weaklyδ-continuous, weakly open and almost open functions. Additional characterizations are given for weaklyδ-continuous functions. The concept ofθ-neighborhood is also used to define the following types of open maps:θ-open, stronglyθ-open, almost stronglyθ-open, and weaklyδ-open functions.

scholarly journals Ideal theory on EQ-algebras

2021 ◽  
Vol 6 (11) ◽  
pp. 11686-11707
Author(s):  
Jie Qiong Shi ◽  
◽  
Xiao Long Xin ◽  
Keyword(s):  
Topological Space ◽  
Maximal Ideal ◽  
Ideal Theory ◽  
Distributive Lattices ◽  
Prime Ideals ◽  
Topological Properties ◽  
Maximal Ideals ◽  
Primary Ideals ◽  
The Ideal

<abstract><p>In this article, we introduce ideals and other special ideals on EQ-algebras, such as implicative ideals, primary ideals, prime ideals and maximal ideals. At first, we give the notion of ideal and its related properties on EQ-algebras, and give its equivalent characterizations. We discuss the relations between ideals and filters, and study the generating formula of ideals on EQ-algebras. Moreover, we study the properties of implicative ideals, primary ideals, prime ideals and maximal ideals and their relations. For example, we prove that every maximal ideal is prime and if prime ideals are implicative, then they are maximal in the EQ-algebra with the condition $ (DNP) $. Finally, we introduce the topological properties of prime ideals. We get that the set of all prime ideals is a compact $ T_{0} $ topological space. Also, we transferred the spectrum of EQ-algebras to bounded distributive lattices and given the ideal reticulation of EQ-algebras.</p></abstract>

scholarly journals R-continuous functions

1992 ◽  
Vol 15 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Ch. Konstadilaki-Savvapoulou ◽  
D. Janković
Keyword(s):  
Continuous Functions ◽  
Strong Form ◽  
Topological Spaces ◽  
Strong Continuity ◽  
Closed Graph ◽  
Continuity Properties

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.

scholarly journals Diameter-preserving linear bijections of function spaces

2001 ◽  
Vol 70 (3) ◽  
pp. 323-336 ◽  
Author(s):  
T. S. S. R. K. Rao ◽  
A. K. Roy
Keyword(s):  
Maximal Ideal ◽  
Convex Set ◽  
Compact Convex ◽  
Extreme Points ◽  
Continuous Functions ◽  
Ideal Space ◽  
Function Algebras ◽  
Compact Convex Set ◽  
Vector Valued Functions ◽  
Vector Valued

AbstractIn this paper we give a complete description of diameter-preserving linear bijections on the space of affine continuous functions on a compact convex set whose extreme points are split faces. We also give a description of such maps on function algebras considered on their maximal ideal space. We formulate and prove similar results for spaces of vector-valued functions.

Real Functions, Covers and Bornologies

2021 ◽  
Vol 78 (1) ◽  
pp. 199-214
Author(s):  
Lev Bukovský
Keyword(s):  
Topological Space ◽  
Pointwise Convergence ◽  
Continuous Functions ◽  
Upper Semicontinuous ◽  
Upper Semicontinuous Functions ◽  
Covering Properties ◽  
Real Functions ◽  
Topology Of Pointwise Convergence ◽  
Semicontinuous Functions

Abstract The paper tries to survey the recent results about relationships between covering properties of a topological space X and the space USC(X) of upper semicontinuous functions on X with the topology of pointwise convergence. Dealing with properties of continuous functions C(X), we need shrinkable covers. The results are extended for A-measurable and upper A-semimeasurable functions where A is a family of subsets of X. Similar results for covers respecting a bornology and spaces USC(X) or C(X) endowed by a topology defined by using the bornology are presented. Some of them seem to be new.

Order continuous measures

1964 ◽  
Vol 60 (2) ◽  
pp. 205-207 ◽  
Author(s):  
G. T. Roberts
Keyword(s):  
Topological Space ◽  
Linear Form ◽  
Vector Lattice ◽  
Measure Zero ◽  
Continuous Functions ◽  
Order Convergence ◽  
Locally Compact ◽  
Compact Topological Space ◽  
Continuous Measures ◽  
Order Continuous

1. Objective. It is possible to define order convergence on the vector lattice of all continuous functions of compact support on a locally compact topological space. Every measure is a linear form on this vector lattice. The object of this paper is to prove that a measure is such that every set of the first category of Baire has measure zero if and only if the measure is a linear form which is continuous in the order convergence.

scholarly journals Contra-continuous functions and stronglyS-closed spaces

1996 ◽  
Vol 19 (2) ◽  
pp. 303-310 ◽  
Author(s):  
J. Dontchev
Keyword(s):  
Dense Subset ◽  
Continuous Functions ◽  
Closed Space ◽  
Closed Sets ◽  
Open Set ◽  
Locally Closed Sets ◽  
Continuous Images

In 1989 Ganster and Reilly [6] introduced and studied the notion ofLC-continuous functions via the concept of locally closed sets. In this paper we consider a stronger form ofLC-continuity called contra-continuity. We call a functionf:(X,τ)→(Y,σ)contra-continuous if the preimage of every open set is closed. A space(X,τ)is called stronglyS-closed if it has a finite dense subset or equivalently if every cover of(X,τ)by closed sets has a finite subcover. We prove that contra-continuous images of stronglyS-closed spaces are compact as well as that contra-continuous,β-continuous images ofS-closed spaces are also compact. We show that every stronglyS-closed space satisfies FCC and hence is nearly compact.

Sign in / Sign up

Export Citation Format

Share Document