scholarly journals On expansive homeomorphism of uniform spaces

2021 ◽  
Vol 13 (2) ◽  
pp. 292-304
Author(s):  
Ali Barzanouni ◽  
Ekta Shah
Keyword(s):  
Uniform Space ◽  
Regular Space ◽  
Uniform Spaces ◽  
Expansive Homeomorphism

Abstract We study the notion of expansive homeomorphisms on uniform spaces. It is shown that if there exists a topologically expansive homeomorphism on a uniform space, then the space is always a Hausdor space and hence a regular space. Further, we characterize orbit expansive homeomorphisms in terms of topologically expansive homeomorphisms and conclude that if there exist a topologically expansive homeomorphism on a compact uniform space then the space is always metrizable.

On ARU-Resolutions of Uniform Spaces

2003 ◽  
Vol 10 (2) ◽  
pp. 201-207
Author(s):  
V. Baladze
Keyword(s):  
Uniform Space ◽  
Uniform Spaces

Abstract In this paper theorems which give conditions for a uniform space to have an ARU-resolution are proved. In particular, a finitistic uniform space admits an ARU-resolution if and only if it has trivial uniform shape or it is an absolute uniform shape retract.

On Homology and Cohomology Groups of Remainders

2004 ◽  
Vol 11 (4) ◽  
pp. 613-633
Author(s):  
V. Baladze ◽  
L. Turmanidze
Keyword(s):  
Uniform Space ◽  
Cohomology Groups ◽  
Uniform Spaces ◽  
Intrinsic Characterization

Abstract Border homology and cohomology groups of pairs of uniform spaces are defined and studied. These groups give an intrinsic characterization of Čech type homology and cohomology groups of the remainder of a uniform space.

scholarly journals A study of uniformities on the space of uniformly continuous mappings

2020 ◽  
Vol 18 (1) ◽  
pp. 1478-1490
Author(s):  
Ankit Gupta ◽  
Abdulkareem Saleh Hamarsheh ◽  
Ratna Dev Sarma ◽  
Reny George
Keyword(s):  
Uniform Space ◽  
Uniform Spaces ◽  
Continuous Mappings ◽  
Uniformly Continuous

Abstract New families of uniformities are introduced on UC(X,Y) , the class of uniformly continuous mappings between X and Y, where (X,{\mathcal{U}}) and (Y,{\mathcal{V}}) are uniform spaces. Admissibility and splittingness are introduced and investigated for such uniformities. Net theory is developed to provide characterizations of admissibility and splittingness of these spaces. It is shown that the point-entourage uniform space is splitting while the entourage-entourage uniform space is admissible.

scholarly journals Compactifications of totally bounded quasi-uniform spaces

1986 ◽  
Vol 28 (1) ◽  
pp. 31-36 ◽  
Author(s):  
P. Fletcher ◽  
W. F. Lindgren
Keyword(s):  
Hausdorff Space ◽  
Uniform Space ◽  
Continuous Extension ◽  
Sufficient Condition ◽  
Uniform Spaces ◽  
Completely Regular ◽  
Totally Bounded ◽  
Continuous Map ◽  
Total Boundedness ◽  
Uniformly Continuous

The notation and terminology of this paper coincide with that of reference [4], except that here the term, compactification, refers to a T1-space. It is known that a completely regular totally bounded Hausdorff quasi-uniform space (X, ) has a Hausdorff compactification if and only if contains a uniformity compatible with ℱ() [4, Theorem 3.47]. The use of regular filters by E. M. Alfsen and J. E. Fenstad [1] and O. Njåstad [5], suggests a construction of a compactification, which differs markedly from the construction obtained in [4]. We use this construction to show that a totally bounded T1 quasi-uniform space has a compactification if and only if it is point symmetric. While it is pleasant to have a characterization that obtains for all T1-spaces, the present construction has several further attributes. Unlike the compactification obtained in [4], the compactification given here preserves both total boundedness and uniform weight, and coincides with the uniform completion when the quasi-uniformity under consideration is a uniformity. Moreover, any quasi-uniformly continuous map from the underlying quasi-uniform space of the compactification onto any totally bounded compact T1-space has a quasi-uniformly continuous extension to the compactification. If is the Pervin quasi-uniformity of a T1-space X, the compactification we obtain is the Wallman compactification of (X, ℱ ()). It follows that our construction need not provide a Hausdorff compactification, even when such a compactification exists; but we obtain a sufficient condition in order that our compactification be a Hausdorff space and note that this condition is satisfied by all uniform spaces and all normal equinormal quasi-uniform spaces. Finally, we note that our construction is reminiscent of the completion obtained by Á. Császár for an arbitrary quasi-uniform space [2, Section 3]; in particular our Theorem 3.7 is comparable with the result of [2, Theorem 3.5].

scholarly journals EXTREMAL EQUILIBRIA FOR DISSIPATIVE PARABOLIC EQUATIONS IN LOCALLY UNIFORM SPACES

2009 ◽  
Vol 19 (11) ◽  
pp. 1995-2037 ◽  
Author(s):  
JAN W. CHOLEWA ◽  
ANÍBAL RODRÍGUEZ-BERNAL
Keyword(s):  
Parabolic Equations ◽  
Uniform Space ◽  
Sufficient Conditions ◽  
Reaction Diffusion ◽  
Stationary Solutions ◽  
Reaction Diffusion Equation ◽  
Asymptotically Stable ◽  
Uniform Spaces ◽  
Integrable Functions ◽  
Convergence Topology

We consider a reaction diffusion equation ut = Δu + f(x, u) in ℝN with initial data in the locally uniform space [Formula: see text], q ∈ [1, ∞), and with dissipative nonlinearities satisfying s f(x, s) ≤ C(x)s2 + D(x) |s|, where [Formula: see text] and [Formula: see text] for certain [Formula: see text]. We construct a global attractor [Formula: see text] and show that [Formula: see text] is actually contained in an ordered interval [φm, φM], where [Formula: see text] is a pair of stationary solutions, minimal and maximal respectively, that satisfy φm ≤ lim inft→∞ u(t; u0) ≤ lim supt→∞ u(t; u0) ≤ φM uniformly for u0 in bounded subsets of [Formula: see text]. A sufficient condition concerning the existence of minimal positive steady state, asymptotically stable from below, is given. Certain sufficient conditions are also discussed ensuring the solutions to be asymptotically small as |x| → ∞. In this case the solutions are shown to enter, asymptotically, Lebesgue spaces of integrable functions in ℝN, the attractor attracts in the uniform convergence topology in ℝN and is a bounded subset of W2,r(ℝN) for some r > N/2. Uniqueness and asymptotic stability of positive solutions are also discussed. Applications to some model problems, including some from mathematical biology are given.

A proof–technique in uniform space theory

2003 ◽  
Vol 68 (3) ◽  
pp. 795-802 ◽  
Author(s):  
Douglas Bridges ◽  
Luminiţa Vîţă
Keyword(s):  
Uniform Space ◽  
Weak Form ◽  
Space Theory ◽  
Proof Technique ◽  
Uniform Spaces ◽  
Constructive Theory ◽  
Law Of Excluded Middle ◽  
The Law ◽  
Excluded Middle

AbstractIn the constructive theory of uniform spaces there occurs a technique of proof in which the application of a weak form of the law of excluded middle is circumvented by purely analytic means. The essence of this proof–technique is extracted and then applied in several different situations.

scholarly journals Quasi-uniform completions of partially ordered spaces

2007 ◽  
Vol 57 (2) ◽  
Author(s):  
David Buhagiar ◽  
Tanja Telenta
Keyword(s):  
Topological Space ◽  
Partial Order ◽  
Uniform Space ◽  
Uniform Spaces ◽  
Natural Conditions ◽  
Ordered Topological Space ◽  
Partially Ordered ◽  
Partially Ordered Topological Space ◽  
Partially Ordered Spaces ◽  
Natural Way

AbstractIn this paper we define partially ordered quasi-uniform spaces (X, $$\mathfrak{U}$$ , ≤) (PO-quasi-uniform spaces) as those space with a biconvex quasi-uniformity $$\mathfrak{U}$$ on the poset (X, ≤) and give a construction of a (transitive) biconvex compatible quasi-uniformity on a partially ordered topological space when its topology satisfies certain natural conditions. We also show that under certain conditions on the topology $$\tau _{\mathfrak{U}*} $$ of a PO-quasi-uniform space (X, $$\mathfrak{U}$$ , ≤), the bicompletion $$(\tilde X,\tilde {\mathfrak{U}})$$ of (X, $$\mathfrak{U}$$ ) is also a PO-quasi-uniform space ( $$(\tilde X,\tilde {\mathfrak{U}})$$ , ⪯) with a partial order ⪯ on $$\tilde X$$ that extends ≤ in a natural way.

scholarly journals Paracompact-type mappings

2021 ◽  
Vol 102 (2) ◽  
pp. 62-66
Author(s):  
B.E. Kanetov ◽  
◽  
A.M. Baidzhuranova ◽  
Keyword(s):  
Uniform Space ◽  
Continuous Mapping ◽  
Uniform Spaces ◽  
Uniform Topology ◽  
Point Space ◽  
Continuous Mappings ◽  
Basic Concepts ◽  
Uniformly Continuous

Recently a new direction of uniform topology called the uniform topology of uniformly continuous mappings has begun to develop intensively. This direction is devoted, first of all, to the extension to uniformly continuous mappings of the basic concepts and statements concerning uniform spaces. In this case a uniform space is understood as the simplest uniformly continuous mapping of this uniform space into a one-point space. The investigations carried out have revealed large uniform analogs of continuous mappings and made it possible to transfer to uniformly continuous mappings many of the main statements of the uniform topology of spaces. The method of transferring results from spaces to mappings makes it possible to generalize many results. Therefore, the problem of extending some concepts and statements concerning uniform spaces to uniformly continuous mappings is urgent. In this article, we introduce and study uniformly R-paracompact, strongly uniformly R-paracompact, and uniformly R-superparacompact mappings. In particular, we solve the problem of preserving R-paracompact (respectively, strongly uniformly R-paracompact, uniformly R-superparacompact) spaces towards the preimage under uniformly R-paracompact (respectively, strongly uniformly R-paracompact, uniformly R-superparacompact) mappings.

scholarly journals A Construction of the Pair Completion of a Quasi-Uniform Space

1978 ◽  
Vol 21 (1) ◽  
pp. 53-59 ◽  
Author(s):  
William F. Lindgren ◽  
Peter Fletcher
Keyword(s):  
Side Effect ◽  
Uniform Space ◽  
Uniform Spaces ◽  
Important Work ◽  
Original Construction

Although L. Nachbin introduced the concept of a quasiuniform space in connection with the study of uniform ordered spaces [7], it was A. Császár who first developed a theory of completion for these spaces. In the review of Császár′s work [3], J. Isbell wrote: “A topogenic space is already complete according to the present definition; an unfortunate side effect is that not every convergent filter is Cauchy.” This aspect of Császár′s theory of completeness seems to have stalled the investigation of its applications, so that even in the study of uniform ordered spaces Császár′s important work has often been overlooked. While it may have seemed that Isbell had pointed out the Achilles′ heel of Császár′s theory, in this paper we outline a construction of Császár′s completion for quasi-uniform spaces, which differs from Császár′s original construction and the construction given by S. Salbany [8], in which Isbell′s objection does not obtain.

Boundedness in a Quasi-Uniform Space

1970 ◽  
Vol 13 (3) ◽  
pp. 367-370 ◽  
Author(s):  
M. G. Murdeshwar ◽  
K. K. Theckedath
Keyword(s):  
Topological Space ◽  
Uniform Space ◽  
Axiomatic Approach ◽  
Finite Union ◽  
Topological Dynamics ◽  
Considerable Importance ◽  
Uniform Spaces

Although a nontopological concept, boundedness seems to be of considerable importance in a topological space. 'There are many topological problems in which it is essential to be able to make this distinction' (between bounded and unbounded sets) [1]. Boundedness and in particular boundedness-preserving' uniform spaces appear to have applications to topological dynamics [4].In spite of this importance, there have been only isolated attempts at developing the concept. Alexander [1] and Hu [7] tried the axiomatic approach. Hu, for example, calls a nonempty family of sets a boundedness if is hereditary and closed under finite union.

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