On \(\Sigma\)-products of semi-stratifiable spaces
The author continues the study of separation properties of \(\Sigma\)- products (i.e. subspaces of infinite Cartesian products of spaces consisting of all points which differ from one fixed point in at most countably many coordinates). Among other results, it is proved that (1) Let \(\Sigma\) be a \(\Sigma\)-product of semi-stratifiable spaces, each finite subproduct of which is paracompact. (a) If \(\Sigma\) has countable tightness then it is normal, (b) If \(\Sigma\) is normal then \(\Sigma\) is collectionwise normal. (2) A \(\Sigma\)-product of semi-stratifiable spaces is subnormal and a P-space.
scientific article; zbMATH DE number 3982028
scientific article