A. Bella, I.V. Yaschenko
On AP and WAP spaces

Comment.Math.Univ.Carolinae 40,3 (1999) 531-536.

Abstract:Several remarks on the properties of approximation by points (AP) and weak approximation by points (WAP) are presented. We look in particular at their behavior in product and at their relationships with radiality, pseudoradiality and related concepts. For instance, relevant facts are: \par \noindent (a) There is in ZFC a product of a countable WAP space with a convergent sequence which fails to be WAP. \par \noindent (b) $C_p$ over $\sigma $-compact space is AP. Therefore AP does not imply even pseudoradiality in function spaces, while it implies Fr\'echet-Urysohn property in compact spaces. \par \noindent (c) WAP and AP do not coincide in $C_p$.

Keywords: AP space, WAP space, pseudoradial space, radial space, product, compact space, submaximal space, function space
AMS Subject Classification: 54A25, 54D55