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1.
Order Environments of Topological Spaces 总被引:1,自引:0,他引:1
J.H.LIANG K.KEIMEL 《数学学报(英文版)》2004,20(5):943-948
In this paper it is proved that a space may be realized as the set of the maximal elements in a continuous poset if and only if it is Tychonoff. 相似文献
2.
Omar De la Cruz Eric Hall Paul Howard Kyriakos Keremedis Jean E. Rubin 《Mathematical Logic Quarterly》2003,49(1):57-71
This is a continuation of [2]. We study the Tychonoff Compactness Theorem for various definitions of compactness and for various types of spaces (first and second countable spaces, Hausdorff spaces, and subspaces of ?K). We also study well ordered Tychonoff products and the effect that the multiple choice axiom has on such products. 相似文献
3.
R. I. Grigorchuk 《Mathematical Notes》1996,60(3):274-282
The paper is devoted to the study of weights on groups. A connection between weight functions and harmonic functions is established.
A relationship between the weight theory on groups with the “Tychonoff property” and the theory of bounded cohomology is presented.
It is proved that the Beurling algebraℓ1 (G, ω) constructed for the weightω is amenable if and only if the groupG is amenable and the weightω is equivalent to a multiplicative characterχ:G→ℝ+.
Translated fromMatematicheskie Zametki, Vol. 60, No. 3, pp. 448–460, September, 1996.
This research was partially supported by the Russian Foundation for Basic Research under grant No. 96-01-00974 and by the
INTAS Foundation under grant No. 94-3420. 相似文献
4.
In this note,we present that:(1)Let X=σ{Xα:α∈A} be|A|-paracompact (resp.,hereditarily |A|-paracompact).If every finite subproduct of {Xα:α∈A} has property b1 (resp.,hereditarily property b1),then so is X.(2) Let X be a P-space and Y a metric space.Then,X×Y has property b1 iff X has property b1.(3) Let X be a strongly zero-dimensional and compact space.Then,X×Y has property b1 iff Y has property b1. 相似文献
5.
E. M. Vechtomov 《Mathematical Notes》1997,62(5):575-580
The latticeA(X) of all possible subalgebras of the ring of all continuous ℝ-valued functions defined on an ℝ-separated spaceX is considered. A topological space is said to be a Hewitt space if it is homeomorphic to a closed subspace of a Tychonoff
power of the real line ℝ. The main achievement of the paper is the proof of the fact that any Hewitt spaceX is determined by the latticeA(X). An original technique of minimal and maximal subalgebras is applied. It is shown that the latticeA(X) is regular if and only ifX contains at most two points.
Translated fromMatematicheskie Zametki, Vol. 62, No. 5, pp. 687–693, November, 1997.
Translated by A. I. Shtern 相似文献
6.
The inclusion hyperspace functor, the capacity functor and monads for these functors have been extended from the category of compact Hausdorff spaces to the category of Tychonoff spaces. Properties of spaces and maps of inclusion hyperspaces and capacities (non-additive measures) on Tychonoff spaces are investigated. 相似文献
7.
Kyriakos Keremedis 《Mathematical Logic Quarterly》2010,56(5):475-487
Let {(Xi, Ti): i ∈I } be a family of compact spaces and let X be their Tychonoff product. ??(X) denotes the family of all basic non‐trivial closed subsets of X and ??R(X) denotes the family of all closed subsets H = V × ΠXi of X, where V is a non‐trivial closed subset of ΠXi and QH is a finite non‐empty subset of I. We show: (i) Every filterbase ?? ? ??R(X) extends to a ??R(X)‐ultrafilter ? if and only if every family H ? ??(X) with the finite intersection property (fip for abbreviation) extends to a maximal ??(X) family F with the fip. (ii) The proposition “if every filterbase ?? ? ??R(X) extends to a ??R(X)‐ultrafilter ?, then X is compact” is not provable in ZF. (iii) The statement “for every family {(Xi, Ti): i ∈ I } of compact spaces, every filterbase ?? ? ??R(Y), Y = Πi ∈IYi, extends to a ??R(Y)‐ultrafilter ?” is equivalent to Tychonoff's compactness theorem. (iv) The statement “for every family {(Xi, Ti): i ∈ ω } of compact spaces, every countable filterbase ?? ? ??R(X), X = Πi ∈ωXi, extends to a ??R(X)‐ultrafilter ?” is equivalent to Tychonoff's compactness theorem restricted to countable families. (v) The countable Axiom of Choice is equivalent to the proposition “for every family {(Xi, Ti): i ∈ ω } of compact topological spaces, every countable family ?? ? ??(X) with the fip extends to a maximal ??(X) family ? with the fip” (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Gerald Beer 《Set-Valued Analysis》2008,16(4):477-488
A bornological universe 〈X, τ, ℬ〉 is a topological space 〈X, τ〉 equipped with a bornology ℬ, that is, a cover of X that is hereditary and is closed under finite unions. In this paper, we give three different sets of necessary and sufficient
conditions for the universe to be both topologically and bornologically embeddable in ℝ
Y
for some index set Y. When this is possible, Y can be chosen to be a family of continuous coercive functions on X.
Dedicated to Arrigo Cellina. 相似文献
9.
Kyriakos Keremedis 《Mathematical Logic Quarterly》2000,46(4):569-571
We show that for every we ordered cardinal number m the Tychonoff product 2m is a compact space without the use of any choice but in Cohen's Second Mode 2ℝ is not compact. 相似文献
10.
Several results on rectangular products in the sense of B.A. Pasynkov will be obtained, one of which asserts that for a Tychonoff space X, X × Y is rectangular for any space Y iff X is locally compact and paracompact. 相似文献