On γ−countably paracompact sets

In this paper we introduce and study a new class of sets, namely γ−countably paracompact sets. We characterize γ−countably paracompact sets and we study some of its basic properties. We obtain that this class of sets is weaker than α−countably paracompact sets and stronger than β−countably paracompact sets.

Characterizations of Strongly Paracompact Spaces

Characterizations of strongly compact spaces are given based on the existence of a star-countable open refinement for every increasing open cover. It is proved that a countably paracompact normal space (a perfectly normal space or a monotonically normal space) is strongly paracompact if and only if every increasing open cover of the space has a star-countable open refinement. Moreover, it is shown that a space is linearlyDprovided that every increasing open cover of the space has a point-countable open refinement.

The Normality in Products with a Countably Compact Factor

It is known that the product ω1 × X of ω1 with an M1-spacemay be nonnormal. In this paper we prove that the product κ × X of an uncountable regular cardinal κ with a paracompact semi-stratifiable space is normal iff it is countably paracompact. We also give a sufficient condition under which the product of a normal space with a paracompact space is normal, from which many theorems involving such a product with a countably compact factor can be derived.