Geodesic
A strengthening of the Katětov-Tong insertion theorem
Commentationes Mathematicae Universitatis Carolinae, Tome 34 (1993) no. 2, pp. 357-362.

Voir la notice de l'article provenant de la source Czech Digital Mathematics Library

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.
Classification : 54C30, 54D15
Keywords: normal space; semicontinuous functions; insertion; limit functions; completely normal space 
@article{CMUC_1993__34_2_a17,
     author = {Kubiak, Tomasz},
     title = {A strengthening of the {Kat\v{e}tov-Tong} insertion theorem},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {357--362},
     publisher = {mathdoc},
     volume = {34},
     number = {2},
     year = {1993},
     mrnumber = {1241744},
     zbl = {0807.54023},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1993__34_2_a17/}
}
TY  - JOUR
AU  - Kubiak, Tomasz
TI  - A strengthening of the Katětov-Tong insertion theorem
JO  - Commentationes Mathematicae Universitatis Carolinae
PY  - 1993
SP  - 357
EP  - 362
VL  - 34
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/CMUC_1993__34_2_a17/
LA  - en
ID  - CMUC_1993__34_2_a17
ER  - 
%0 Journal Article
%A Kubiak, Tomasz
%T A strengthening of the Katětov-Tong insertion theorem
%J Commentationes Mathematicae Universitatis Carolinae
%D 1993
%P 357-362
%V 34
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMUC_1993__34_2_a17/
%G en
%F CMUC_1993__34_2_a17
Kubiak, Tomasz. A strengthening of the Katětov-Tong insertion theorem. Commentationes Mathematicae Universitatis Carolinae, Tome 34 (1993) no. 2, pp. 357-362. http://geodesic.mathdoc.fr/item/CMUC_1993__34_2_a17/