Strong gamma-sets and other singular spaces

Abstract

Whereas the Gerlits-Nagy gamma-property is strictly weaker than the Galvin-Miller strong gamma-property, the corresponding strong notions for the Menger, Hurewicz, Rothberger, Gerlits-Nagy (*), Arkhangel'skii and Sakai properties are equivalent to the original ones. The main result is that almost each of these properties admits the game theoretic characterization suggested by the stronger notion. We also solve a related problem of Kocinac and Scheepers, and answer a question of Iliadis.