Abstract
We investigate the Whyburn and weakly Whyburn property in the class of P-spaces, that is spaces where every countable intersection of open sets is open. We construct examples of non-weakly Whyburn P-spaces of size continuum, thus giving a negative answer under CH to a question of Pelant, Tkachenko, Tkachuk and Wilson ([13]). In addition, we show that the weak Kurepa Hypothesis (an assumption weaker than CH) implies the existence of a non-weakly Whyburn P-space of size N2. Finally, we consider the behavior of the above-mentioned properties under products; we show in particular that the product of a Lindelöf weakly Whyburn P-space and a Lindelöf Whyburn P-space is weakly Whyburn, and we give a consistent example of a non-Whyburn product of two Lindelöf Whyburn P-spaces.
| Original language | English |
|---|---|
| Pages (from-to) | 995-1015 |
| Number of pages | 21 |
| Journal | Houston Journal of Mathematics |
| Volume | 37 |
| Issue number | 3 |
| State | Published - 26 Dec 2011 |
Keywords
- Almost disjoint family
- Cardinality
- Continuum hypothesis
- Extent
- Lindelöf space
- Nowhere mad family
- P-space
- Pseudocharacter
- Pseudoradial space
- Radial character
- Radial space
- Weak Kurepa tree
- Weakly Whyburn space
- Weight
- Whyburn space
- ω-Modification
ASJC Scopus subject areas
- General Mathematics