Zobrazeno 1 - 10
of 60
pro vyhledávání: '"Jack R. Porter"'
Publikováno v:
Applied General Topology, Vol 5, Iss 2, Pp 243-264 (2004)
Every first countable pseudocompact Tychonoff space X has the property that every pseudocompact subspace of X is a closed subset of X (denoted herein by “FCC”). We study the property FCC and several closely related ones, and focus on the behavior
Externí odkaz:
https://doaj.org/article/b78b0f677e5c4d1fbdbe258c4f175662
Publikováno v:
Acta Mathematica Hungarica. 159:109-123
We introduce the class of $$\theta^n$$ -Urysohn spaces and the $$n$$ - $$\theta$$ -closure operator. $$\theta^n$$ -Urysohn spaces generalize the notion of a Urysohn space and we consider their relationship with S(n)-spaces, studied in [9], [14] and [
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::ea906a6c3d1e5d167593b9dbd3a15ed3
https://doi.org/10.1007/s10474-019-00981-y
https://doi.org/10.1007/s10474-019-00981-y
Publikováno v:
SSRN Electronic Journal.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::479c354dcca49bd7c20b64d8b3ad612e
https://doi.org/10.2139/ssrn.3889131
https://doi.org/10.2139/ssrn.3889131
Publikováno v:
SSRN Electronic Journal.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::28e354cb44065638e6d7054f38924aad
https://doi.org/10.2139/ssrn.3901588
https://doi.org/10.2139/ssrn.3901588
Autor:
Jack R. Porter, Nathan Carlson
Publikováno v:
Topology and its Applications. 241:377-395
We introduce the cardinal invariant a L ′ ( X ) and show that | X | ≤ 2 a L ′ ( X ) χ ( X ) for any Hausdorff space X (a corollary of Theorem 4.4 ). This invariant has the properties a) a L ′ ( X ) = ℵ 0 if X is H-closed, and b) a L ( X )
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::47aaa7ec8bc251c19d94093f7bb57849
https://doi.org/10.1016/j.topol.2017.01.027
https://doi.org/10.1016/j.topol.2017.01.027
Autor:
Jack R. Porter, N.A. Carlson
Publikováno v:
Topology and its Applications. 202:239-250
We introduce a modified closing-off argument that results in several improved bounds for the cardinalities of Hausdorff and Urysohn spaces. These bounds involve the cardinal invariant skL ( X , λ ) , the skew-λ Lindelof degree of a space X, where
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b12e57dfbad0c19da71a9e170866be43
https://doi.org/10.1016/j.topol.2016.01.012
https://doi.org/10.1016/j.topol.2016.01.012
In this paper we extend the theory of H-closed extensions of Hausdorff spaces to a class of non-Hausdorff spaces, defined in \cite{B}, called $n$-Hausdorff spaces. The notion of H-closed is generalized to an $n$-H-closed space. Known construction for
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3bc7ebb218ef9db0389b443de242e5b7
Publikováno v:
Topology and its Applications. 160(1):137-142
A common generalization for two of the main streams of cardinality inequalities is developed; each stream derives from the famous inequality established by A.V. Arhangel'ski\u{\i} in 1969 for Hausdorff spaces. At the end of one stream is the recent i
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2f8350c4edfcc3ca3e66e22e8fa56d79
Publikováno v:
Filomat. 27:1107-1111
The research in this paper is a continuation of the investigation of the cardinality of the $��$-closed hull of subsets of spaces. This research obtains new upper bounds of the cardinality of the $��$-closed hull of subsets using cardinal fun
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::abea4fe64d4821c7809e136593ef5e4c
https://doi.org/10.2298/fil1306107c
https://doi.org/10.2298/fil1306107c
Publikováno v:
Topology and its Applications. 159:2932-2941
Improving a result in Carlson and Ridderbos (2012) [9], we construct a closing-off argument showing that the Lindelof degree of the Gκ-modification of a space X is at most 2L(X)F(X)⋅κ, where F(X) is the supremum of the lengths of all free sequenc
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::436e954a4b3593139ae7fed509177a9e
https://doi.org/10.1016/j.topol.2012.05.004
https://doi.org/10.1016/j.topol.2012.05.004