On movable compacta
On multifunctions with closed graphs
The set of points of upper semicontinuity of multi-valued mappings with a closed graph is studied. A topology on the space of multi-valued mappings with a closed graph is introduced.
On multifunctions with convex graph
In questa Nota viene stabilita una caratterizzazione generale della semicontinuità inferiore delle multifunzioni, a grafico convesso, definite in sottoinsieme non vuoto, aperto e convesso di uno spazio vettoriale topologico e a valori in uno spazio vettoriale topologico localmente convesso. Sono poste in luce, poi, varie conseguenze di tale caratterizzazione.
On multisequences and their application to products of sequential spaces
On multi-valued functions.
On multivalued quotient mappings
On multivalued quotient mappings.
On -in-countable bases
Some results concerning spaces with countably weakly uniform bases are generalized for spaces with -in-countable ones.
On --normal and --quasinormal semi-Hilbertian space operators
The purpose of the paper is to introduce and study a new class of operators on semi-Hilbertian spaces, i.e. spaces generated by positive semi-definite sesquilinear forms. Let be a Hilbert space and let be a positive bounded operator on . The semi-inner product , , induces a semi-norm . This makes into a semi-Hilbertian space. An operator is said to be --normal if for some positive integers and .
On N. Noble's theorems concerning powers of spaces and mappings
On -thin dense sets in powers of topological spaces
A subset of a product of topological spaces is called -thin if every its two distinct points differ in at least coordinates. We generalize a construction of Gruenhage, Natkaniec, and Piotrowski, and obtain, under CH, a countable space without isolated points such that contains an -thin dense subset, but does not contain any -thin dense subset. We also observe that part of the construction can be carried out under MA.
On Nachbin's problem concerning uniformizable ordered spaces
On Nash theorem
On natural merotopies
On natural metrics.
In the present note we study the effective construction of a natural generalized metric structure (on a set), obtaining as particular case the result of Menger. In the case of groups, we analyze its topology and its structure of natural proximity space (in the sense of Efremovic).
On nearly paracompact spaces
On Nearly Paracompact Spaces
On Nearly Paracompact Spaces and Nearly Full Normality
On Nearly Paracompact Spaces via Regular Even Covers
On nearly strongly paracompact and almost-strongly paracompact spaces.