Here is the list of posts on places where countability matters in topology, so far:
- The Dolecki-Greco-Lechicki theorem
- Some new, easy facts on consonant spaces
- The Sorgenfrey line is not consonant
- Q is not consonant: the Costantini-Watson argument
- Strongly compact sets and the double hyperspace construction
- On Till Plewe’s game and Matthew de Brecht’s non-consonance arguments
- Localic products and Till Plewe’s game