Abstract
The notions of an Sδ set and an Rδ set are introduced. A space is S-perfect (R-perfect) if each closed set is an Sδ set (Rδ) set. Conditions are given which indicate when spaces are S-perfect or R-perfect. Examples are given of spaces which do not have these properties and examples are given of spaces with these properties that are not perfect spaces. The images of S-perfect and R-perfect spaces under various types of mappings are investigated.
Original language | English |
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Pages (from-to) | 247-264 |
Number of pages | 18 |
Journal | Topology and its Applications |
Volume | 33 |
Issue number | 3 |
DOIs | |
State | Published - Nov 1989 |
Keywords
- Baire sets
- R-perfect
- S-perfect
- co-analytic sets
- open-compact maps
- perfect maps
- perfect sets