scholarly journals C-normal topological property

Filomat ◽  
2017 ◽  
Vol 31 (2) ◽  
pp. 407-411 ◽  
Author(s):  
Samirah AlZahrani ◽  
Lutfi Kalantan

A topological space X is called C-normal if there exist a normal space Y and a bijective function f : X ? Y such that the restriction f _ C : C ? f (C) is a homeomorphism for each compact subspace C ? X. We investigate this property and present some examples to illustrate the relationships between C-normality and other weaker kinds of normality.

2021 ◽  
Vol 12 (6) ◽  
pp. 1-8
Author(s):  
LUTFI KALANTAN ◽  
MAI MANSOURI

A topological space X is called P-normal if there exist a normal space Y and a bijective function f : X −→ Y such that the restriction f|A : A −→ f(A) is a homeomorphism for each paracompact subspace A ⊆ X. We will investigate this property and produce some examples to illustrate the relation between P-normality and other weaker kinds of normality.


2021 ◽  
Vol 14 (2) ◽  
pp. 351-357
Author(s):  
Hala Alzumi ◽  
Lutfi Kalantan ◽  
Maha Mohammed Saeed

A C-paracompact is a topological space X associated with a paracompact space Y and a bijective function f : X −→ Y satisfying that f A: A −→ f(A) is a homeomorphism for each compact subspace A ⊆ X. Furthermore, X is called C2-paracompact if Y is T2 paracompact. In this article, we discuss the above concepts and answer the problem of Arhangel’ski ̆i. Moreover, we prove that the sigma product Σ(0) can not be condensed onto a T2 paracompact space.


NUTA Journal ◽  
2020 ◽  
Vol 7 (1-2) ◽  
pp. 68-70
Author(s):  
Raj Narayan Yadav ◽  
Bed Prasad Regmi ◽  
Surendra Raj Pathak

A property of a topological space is termed hereditary ifand only if every subspace of a space with the property also has the property. The purpose of this article is to prove that the topological property of separable space is hereditary. In this paper we determine some topological properties which are hereditary and investigate necessary and sufficient condition functions for sub-spaces to possess properties of sub-spaces which are not in general hereditary.


1962 ◽  
Vol 14 ◽  
pp. 461-466 ◽  
Author(s):  
Isaac Namioka

Let Δn (n > 0) denote the subset of the Euclidean (n + 1)-dimensional space defined byA subset σ of Δn is called a face if there exists a sequence 0 ≤ i1 ≤ i2 ≤ … < im ≤ n such thatand the dimension of σ is defined to be (n — m). Let denote the union of all faces of Δn of dimensions less than n. A topological space Y is called solid if any continuous map on a closed subspace A of a normal space X into Y can be extended to a map on X into Y. By Tietz's extension theorem, each face of Δn is solid. The present paper is concerned with a generalization of the following theorem which seems well known.


1981 ◽  
Vol 23 (1) ◽  
pp. 1-4
Author(s):  
D.B. Gauld ◽  
I.L. Reilly ◽  
M.K. Vamanamurthy

In this paper the anti-normal property is studied. A space is anti-normal if its only normal subspaces are those whose cardinalities require them to be normal. It is shown that every topological space of at least four elements contains a normal three point subspace from which it follows that there is only one non-trivial anti-normal space.


2019 ◽  
Vol 24 (5) ◽  
pp. 111
Author(s):  
Taha H. Jasim1 ◽  
Luma H. Othman

The purpose of this paper is to introduce a new class of completely normal spaces namely , ) completely normal space . The relationship between them was studied and we investigate some characterizations of them. At last we give more of examples to explain the subject and study the topological property and hereditary property of these types.   http://dx.doi.org/10.25130/tjps.24.2019.099


2017 ◽  
Vol 20 (10) ◽  
pp. 68-73
Author(s):  
O.I. Pavlov

One of the central tasks in the theory of condensations is to describe topological properties that can be improved by condensation (i.e. a continuous one-to-one mapping). Most of the known counterexamples in the field deal with non-hereditary properties. We construct a countably compact linearly ordered (hence, monotonically normal, thus ” very strongly” hereditarily normal) topological space whose square and higher powers cannot be condensed onto a normal space. The constructed space is necessarily pseudocompact in all the powers, which complements a known result on condensations of non-pseudocompact spaces.


2018 ◽  
Vol 11 (3) ◽  
pp. 882-892 ◽  
Author(s):  
Samirah ALZahrani

A topological space X is called C-Tychonoff if there exist a one-to-one function f from X onto a Tychonoff space Y such that f restriction K from K onto f(K) is a homeomorphism for each compact subspace K of X. We discuss this property and illustrate the relationships between C-Tychonoffness and some other properties like submetrizability, local compactness, L-Tychononess, C-normality, C-regularity, epinormality, sigma-compactness, pseudocompactness and zero-dimensional.


2000 ◽  
Vol 6 (1) ◽  
pp. 3-23 ◽  
Author(s):  
Jan Cupal ◽  
Stephan Kopp ◽  
Peter F. Stadler

The distinction between continuous and discontinuous transitions is a long-standing problem in the theory of evolution. Because continuity is a topological property, we present a formalism that treats the space of phenotypes as a (finite) topological space, with a topology that is derived from the probabilities with which one phenotype is accessible from another through changes at the genotypic level. The shape space of RNA secondary structures is used to illustrate this approach. We show that evolutionary trajectories are continuous if and only if they follow connected paths in phenotype space.


1986 ◽  
Vol 29 (2) ◽  
pp. 154-159
Author(s):  
Hans-Peter Künzi ◽  
Peter Fletcher

AbstractA topological space X is said to be somewhat normal provided that for each open cover is a normal cover of X. We show that a completely regular somewhat normal space need not be normal, thereby answering a question of W. M. Fleischman. We note that a collectionwise normal somewhat normal space need not be almost 2-fully normal, as had previously been asserted, and that neither the perfect image nor the perfect preimage of a somewhat normal space has to be somewhat normal.


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