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Topological characterization of the small cardinal i

Antonio de Padua Franco-Filho (2003)

Commentationes Mathematicae Universitatis Carolinae

We show that the small cardinal number i = min { | 𝒜 | : 𝒜 is a maximal independent family} has the following topological characterization: i = min { κ c : { 0 , 1 } κ has a dense irresolvable countable subspace}, where { 0 , 1 } κ denotes the Cantor cube of weight κ . As a consequence of this result, we have that the Cantor cube of weight c has a dense countable submaximal subspace, if we assume (ZFC plus i = c ), or if we work in the Bell-Kunen model, where i = 1 and c = ω 1 .

Topological compactifications

Benjamin Vejnar (2011)

Fundamenta Mathematicae

We study those compactifications of a space such that every autohomeomorphism of the space can be continuously extended over the compactification. These are called H-compactifications. Van Douwen proved that there are exactly three H-compactifications of the real line. We prove that there exist only two H-compactifications of Euclidean spaces of higher dimension. Next we show that there are 26 H-compactifications of a countable sum of real lines and 11 H-compactifications of a countable sum of Euclidean...

Topological degree theory in fuzzy metric spaces

M.H.M. Rashid (2019)

Archivum Mathematicum

The aim of this paper is to modify the theory to fuzzy metric spaces, a natural extension of probabilistic ones. More precisely, the modification concerns fuzzily normed linear spaces, and, after defining a fuzzy concept of completeness, fuzzy Banach spaces. After discussing some properties of mappings with compact images, we define the (Leray-Schauder) degree by a sort of colimit extension of (already assumed) finite dimensional ones. Then, several properties of thus defined concept are proved....

Topological disjointness from entropy zero systems

Wen Huang, Kyewon Koh Park, Xiangdong Ye (2007)

Bulletin de la Société Mathématique de France

The properties of topological dynamical systems ( X , T ) which are disjoint from all minimal systems of zero entropy, 0 , are investigated. Unlike the measurable case, it is known that topological K -systems make up a proper subset of the systems which are disjoint from 0 . We show that ( X , T ) has an invariant measure with full support, and if in addition ( X , T ) is transitive, then ( X , T ) is weakly mixing. A transitive diagonal system with only one minimal point is constructed. As a consequence, there exists a thickly syndetic...

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