Results 21 to 30 of about 60 (60)
Perfect maps in compact (countably compact) spaces
International Journal of Mathematics and Mathematical Sciences, Volume 18, Issue 4, Page 773-776, 1995., 1993 In this paper, among other results, characterizations of perfect maps in compact Hausdorff(Fréchet, countably compact, Hausdorff) spaces are obtained.
G. L. Garg, Asha Goel
wiley +1 more source
Measures of Lindelof and separability in approach spaces
International Journal of Mathematics and Mathematical Sciences, Volume 17, Issue 3, Page 597-606, 1994., 1993 In this paper we introduce the notions of separability and Lindelöf in approach spaces and investigate their behaviour under products and subspaces.
R. Baekeland, R. Lowen
wiley +1 more source
International Journal of Mathematics and Mathematical Sciences, Volume 17, Issue 4, Page 687-692, 1994., 1994 In this paper we study θ‐regularity and its relations to other topological properties. We show that the concepts of θ‐regularity (Janković, 1985) and point paracompactness (Boyte, 1973) coincide. Regular, strongly locally compact or paracompact spaces are θ‐regular.
Martin M. Kovár
wiley +1 more source
On weaker forms of compactness Lindelöfness and countable compactness
International Journal of Mathematics and Mathematical Sciences, Volume 13, Issue 1, Page 55-59, 1990., 1988 A theory of e‐countable compactness and e‐Lindelöfness which are weaker than the concepts of countable compactness and Lindelöfness respectively is developed. Amongst other results we show that an e‐countably compact space is pseudocompact, and an example of a space which is pseudocompact but not e‐countably compact with respect to any dense set is ...
D. Baboolal, J. Backhouse, R. G. Ori
wiley +1 more source
Applications of δ‐Open Sets via Separation Axioms, Covering Properties, and Rough Set Models
Journal of Mathematics, Volume 2025, Issue 1, 2025.In this article, we make use of δ‐open sets to establish some topological concepts related to separation axioms and covering properties and to propose novel topological rough set models. We first demonstrate that the classes of regular‐open and δ‐open subsets of a finite topological space are equivalent when this space has the property of ∂(A)∩∂(B)⊆∂(A
Tareq M. Al-Shami +2 more
wiley +1 more source
International Journal of Mathematics and Mathematical Sciences, Volume 13, Issue 3, Page 507-512, 1990., 1989 An ideal on a set X is a nonempty collection of subsets of X closed under the operations of subset (heredity) and finite unions (additivity). Given a topological space (X, τ) an ideal ℐ on X and A⊆X, ψ(A) is defined as ⋃{U ∈ τ : U − A ∈ ℐ}. A topology, denoted τ*, finer than τ is generated by the basis {U − I : U ∈ τ, I ∈ ℐ}, and a topology, denoted 〈ψ(
T. R. Hamlett, David Rose
wiley +1 more source
A topological property of β(N)
International Journal of Mathematics and Mathematical Sciences, Volume 3, Issue 4, Page 713-717, 1980., 1980 In this paper we prove that the Stone‐Cech‐compactification of the natural numbers does not admit a countable infinite decomposition into subsets homeomorphic to each other and to the said compactification.
Anastase Nakassis
wiley +1 more source
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 +2 more
core
© Hindawi Publishing Corp. QUANTIFICATION OF TOPOLOGICAL CONCEPTS USING IDEALS
, 2000 . We introduce certain ideals of real-valued functions as a natural generalization of filters. We show that these ideals establish a canonical framework for the quantification of topological concepts, such as closedness, adherence, and compactness, in ...
Robert Lowen, Bart Windels
core
, 2004 It is shown that the categories of stably continuous σ-frames and compact regular σ-biframes are equivalent. This is the analogue of Banaschewski and Brümmer [1], linking the stably continuous frames and compact regular biframes ...
Matutu, Phethiwe
core