On PSigma and Weakly PSigma Spaces
On pushing out frames
On reflexive closed set lattices
For a topological space , let denote the set of all closed subsets in , and let denote the set of all continuous maps . A family is called reflexive if there exists such that for every . Every reflexive family of closed sets in space forms a sub complete lattice of the lattice of all closed sets in . In this paper, we continue to study the reflexive families of closed sets in various types of topological spaces. More necessary and sufficient conditions for certain families of closed...
On shape and fundamental deformation retracts II
On shape of hyperspaces
On some maps concerning -open sets.
On some metrizations of the hyperspace of compact sets
On some operation on sets of mappings
On some spaces which are covered by a product space
In this note, a topological version of the results obtained, in connection with the de Rham reducibility theorem (Comment. Math. Helv., 26 ( 1952), 328–344), by S. Kashiwabara (Tôhoku Math. J., 8 (1956), 13–28), (Tôhoku Math. J., 11 (1959), 327–350) and Ia. L. Sapiro (Izv. Bysh. Uceb. Zaved. Mat. no6, (1972), 78–85, Russian), (Izv. Bysh. Uceb. Zaved. Mat. no4, (1974), 104–113, Russian) is given. Thus a characterization of a class of topological spaces covered by a product space is obtained and the...
On Some Spaces which can be Partioned by the Rational Line.
On some subspaces of the Helly space
On spaces whose product with every Lindelöf space is Lindelöf
On spaces with the property of weak approximation by points
A sufficient condition that the product of two compact spaces has the property of weak approximation by points (briefly WAP) is given. It follows that the product of the unit interval with a compact WAP space is also a WAP space.
On -starcompact spaces.
On -starcompact spaces
A space is -starcompact if for every open cover of there exists a Lindelöf subset of such that We clarify the relations between -starcompact spaces and other related spaces and investigate topological properties of -starcompact spaces. A question of Hiremath is answered.
On subsets of Alexandroff duplicates
We characterize the subsets of the Alexandroff duplicate which have a G-diagonal and the subsets which are M-spaces in the sense of Morita.
On subspaces of pseudo-radial spaces
It is proved that, under the Martin’s Axiom, every -space with countable tightness is a subspace of some pseudo-radial space. We also give several characterizations of subspaces of pseudo-radial spaces and conclude that being a subspace of a pseudo-radial space is a local property.
On subspaces of the Pixley-Roy example
On supercomplete uniform spaces IV: Countable products
On supercomplete uniform spaces V: Tamano's product problem