scholarly journals Remarks on neighborhood star-Lindelöf spaces II

Filomat ◽  
2013 ◽  
Vol 27 (5) ◽  
pp. 875-880
Author(s):  
Yan-Kui Song
Keyword(s):  
Open Cover ◽  
Countable Subset ◽  
Topological Properties ◽  
Pseudocompact Spaces ◽  
The Relationship

A space X is said to be neighborhood star-Lindel?f if for every open cover U of X there exists a countable subset A of X such that for every open O?A, X=St(O,U). In this paper, we continue to investigate the relationship between neighborhood star-Lindel?f spaces and related spaces, and study topological properties of neighborhood star-Lindel?f spaces in the classes of normal and pseudocompact spaces. .

Some remarks on almost star countable spaces

2015 ◽  
Vol 52 (1) ◽  
pp. 12-20
Author(s):  
Yan-Kui Song
Keyword(s):  
Open Cover ◽  
Countable Subset ◽  
Topological Properties ◽  
Star Countable

A space X is almost star countable (weakly star countable) if for each open cover U of X there exists a countable subset F of X such that \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $\bigcup {_{x \in F}\overline {St\left( {x,U} \right)} } = X$ \end{document} (respectively, \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $\overline {\bigcup {_{x \in F}} St\left( {x,U} \right)} = X$ \end{document}. In this paper, we investigate the relationships among star countable spaces, almost star countable spaces and weakly star countable spaces, and also study topological properties of almost star countable spaces.

scholarly journals On the Set Version of Selectively Star-CCC Spaces

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Ljubiša D. R. Kočinac ◽  
Sumit Singh
Keyword(s):  
Nonempty Subset ◽  
Topological Properties ◽  
Open Problems ◽  
The Relationship

A space X is said to be set selectively star-ccc if for each nonempty subset B of X , for each collection U of open sets in X such that B ¯ ⊂ ∪ U , and for each sequence A n : n ∈ ℕ of maximal cellular open families in X , there is a sequence A n : n ∈ ℕ such that, for each n ∈ ℕ , A n ∈ A n and B ⊂ St ∪ n ∈ ℕ A n , U . In this paper, we introduce set selectively star-ccc spaces and investigate the relationship between set selectively star-ccc and other related spaces. We also study the topological properties of set selectively star-ccc spaces. Some open problems are posed.

scholarly journals Mappings and decompositions of continuity on almost Lindelöf spaces

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
A. J. Fawakhreh ◽  
A. Kiliçman
Keyword(s):  
Topological Space ◽  
Open Cover ◽  
Countable Subset

A topological spaceXis said to be almost Lindelöf if for every open cover{Uα:α∈Δ}ofXthere exists a countable subset{αn:n∈ℕ}⊆Δsuch thatX=∪n∈ℕCl(Uαn). In this paper we study the effect of mappings and some decompositions of continuity on almost Lindelöf spaces. The main result is that a image of an almost Lindelöf space is almost Lindelöf.

scholarly journals Winding number selection on merons by Gaussian curvature’s sign

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ricardo Gabriel Elías ◽  
Nicolás Vidal-Silva ◽  
Vagson L. Carvalho-Santos
Keyword(s):  
Gaussian Curvature ◽  
Domain Walls ◽  
Curved Surfaces ◽  
Two Dimensional ◽  
Winding Number ◽  
Direct Relation ◽  
Topological Properties ◽  
The Core ◽  
Magnetic Surfaces ◽  
The Relationship

Abstract We study the relationship between the winding number of magnetic merons and the Gaussian curvature of two-dimensional magnetic surfaces. We show that positive (negative) Gaussian curvatures privilege merons with positive (negative) winding number. As in the case of unidimensional domain walls, we found that chirality is connected to the polarity of the core. Both effects allow to predict the topological properties of metastable states knowing the geometry of the surface. These features are related with the recently predicted Dzyaloshinskii-Moriya emergent term of curved surfaces. The presented results are at our knowledge the first ones drawing attention about a direct relation between geometric properties of the surfaces and the topology of the hosted solitons.

scholarly journals Application of Algorithmic Manifold to Exponential Time

2017 ◽  
Author(s):  
Takuya Yabu
Keyword(s):  
Turing Machine ◽  
Turing Machines ◽  
Topological Properties ◽  
Exponential Time ◽  
Polynomial Time Algorithms ◽  
Exponential Time Algorithms ◽  
Deterministic Turing Machine ◽  
The Relationship ◽  
Np Problem ◽  
Machine Problem

In the previous paper, I defined algorithmic manifolds simulating polynomial-time algorithms, and I showed topological properties for P problem and NP problem and that NP problem can be transformed into deterministic Turing machine problem.　In this paper, I define algorithmic manifolds simulating exponential-time algorithms and, I show topological properties for EXPTIME problem and NEXPTIME problem. I also discuss the relationship between NEXPTIME and deterministic Turing machines.

scholarly journals LINEARLY ORDERED SPACE WHOSE SQUARE AND HIGHER POWERS CANNOT BE CONDENSED ONTO A NORMAL SPACE

2017 ◽  
Vol 20 (10) ◽  
pp. 68-73
Author(s):  
O.I. Pavlov
Keyword(s):  
Topological Space ◽  
Normal Space ◽  
Topological Properties ◽  
Pseudocompact Spaces ◽  
Countably Compact ◽  
Ordered Space ◽  
One To One ◽  
Hereditary Properties

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.

scholarly journals On star-K-Hurewicz spaces

Filomat ◽  
2017 ◽  
Vol 31 (5) ◽  
pp. 1279-1285 ◽  
Author(s):  
Yan-Kui Song
Keyword(s):  
Topological Properties ◽  
The Relationship ◽  
Compact Subsets

A space X is star-K-Hurewicz if for each sequence (Un : n ? N) of open covers of X there exists a sequence (Kn : n ? N) of compact subsets of X such that for each x ? X, x ? St(Kn,Un) for all but finitely many n. In this paper, we investigate the relationship between star-K-Hurewicz spaces and related spaces by giving some examples, and also study topological properties of star-K-Hurewicz spaces.

Thermodynamic, energetic, and topological properties of crystal packing of pyrazolo[1,5-a]pyrimidines governed by weak electrostatic intermolecular interactions

CrystEngComm ◽  
2015 ◽  
Vol 17 (23) ◽  
pp. 4325-4333 ◽  
Author(s):  
Clarissa P. Frizzo ◽  
Aniele Z. Tier ◽  
Izabelle M. Gindri ◽  
Alexandre R. Meyer ◽  
Gabrielle Black ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Thermodynamic Data ◽  
Crystal Packing ◽  
Topological Properties ◽  
The Relationship

The relationship between energetic and topological properties of crystals with weak electrostatic intermolecular interactions and thermodynamic data are presented.

scholarly journals Algorithmic Manifold and Space Complexity

2017 ◽  
Author(s):  
Takuya Yabu
Keyword(s):  
Time Complexity ◽  
Space Complexity ◽  
Turing Machines ◽  
Topological Properties ◽  
The Relationship

In the previous paper, algorithmic manifolds were applied to the time complexity and discussed.　In this paper, I define algorithmic manifolds expressing space complexity and discuss topological properties. I also discuss the relationship between non-deterministic space complexity problems and deterministic Turing machines.

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