A note on separation of sets by approximately continuous functions
A note on the dimension Dind
A note on weakly hereditarily closure-preserving families.
A perfectly normal locally metrizable non-paracompact space
A Regular Space Without a Uniformly Regular Quasi-Uniformity.
A strengthening of the Katětov-Tong insertion theorem
Normal spaces are characterized in terms of an insertion type theorem, which implies the Katětov-Tong theorem. The proof actually provides a simple necessary and sufficient condition for the insertion of an ordered pair of lower and upper semicontinuous functions between two comparable real-valued functions. As a consequence of the latter, we obtain a characterization of completely normal spaces by real-valued functions.
A subset theorem in dimension theory
A topology generated by eventually different functions
A Tychonoff non-normal space.
A -normal Tychonoff space which is not normal
-normality and -normality are properties generalizing normality of topological spaces. They consist in separating dense subsets of closed disjoint sets. We construct an example of a Tychonoff -normal non-normal space and an example of a Hausdorff -normal non-regular space.
Algunas propiedades del ejemplo de Tychonoff de un espacio regular que no es completamente regular.
Almost -closed functions and separation axioms
We introduce a new class of functions called almost -closed and use the functions to improve several preservation theorems of normality and regularity and also their generalizations. The main result of the paper is that normality and weak normality are preserved under almost -closed continuous surjections.
Almost-n-fully normal spaces
An answer to a question on hyperspaces
An elementary proof of Noble's theorem on normality of powers
Another note on nearly paracompact spaces
Applications of some strong set-theoretic axioms to locally compact T₅ and hereditarily scwH spaces
Under some very strong set-theoretic hypotheses, hereditarily normal spaces (also referred to as T₅ spaces) that are locally compact and hereditarily collectionwise Hausdorff can have a highly simplified structure. This paper gives a structure theorem (Theorem 1) that applies to all such ω₁-compact spaces and another (Theorem 4) to all such spaces of Lindelöf number ≤ ℵ₁. It also introduces an axiom (Axiom F) on crowding of functions, with consequences (Theorem 3) for the crowding of countably compact...
Around Katětov's metrization theorem
Aspects of complete uniform spreads in frames.
Borel extensions of Baire measures in ZFC
We prove: 1) Every Baire measure on the Kojman-Shelah Dowker space admits a Borel extension. 2) If the continuum is not real-valued-measurable then every Baire measure on M. E. Rudin's Dowker space admits a Borel extension. Consequently, Balogh's space remains the only candidate to be a ZFC counterexample to the measure extension problem of the three presently known ZFC Dowker spaces.