Mapping theorems on \(\aleph\)-spaces
The following results are proved: Theorem: \(\aleph\)-spaces (i.e. regular spaces with a \(\sigma\)-locally finite \(\kappa\)-network) are pressed by closed Lindelöf continuous maps (f: \(X\to Y\) is Lindelöf if \(f^{- 1}(y)\) is Lindelöf for each \(y\in Y)\). Theorem. A perfect inverse image of an \(\aleph\)-space is an \(\aleph\)-space iff it has a \(G_{\delta}\)- diagonal or a point-countable \(\kappa\)-network.
scientific article; zbMATH DE number 4084545