Page 1

Displaying 1 – 4 of 4

Showing per page

Weak extent in normal spaces

Ronnie Levy, Mikhail Matveev (2005)

Commentationes Mathematicae Universitatis Carolinae

If X is a space, then the weak extent we ( X ) of X is the cardinal min { α : If 𝒰 is an open cover of X , then there exists A X such that | A | = α and St ( A , 𝒰 ) = X } . In this note, we show that if X is a normal space such that | X | = 𝔠 and we ( X ) = ω , then X does not have a closed discrete subset of cardinality 𝔠 . We show that this result cannot be strengthened in ZFC to get that the extent of X is smaller than 𝔠 , even if the condition that we ( X ) = ω is replaced by the stronger condition that X is separable.

Currently displaying 1 – 4 of 4

Page 1