===== Second-countable space =====
==== Set ====
| @#55CCEE: context     | @#55CCEE: $X$ ... set |
| @#FFBB00: definiendum | @#FFBB00: $\langle X,T\rangle\in$ it |
| @#AAFFAA: inclusion   | @#AAFFAA: $\langle X,T\rangle$ ... topological space |
| @#FFFDDD: exists      | @#FFFDDD: $B\subseteq T$ |
| @#55EE55: postulate   | @#55EE55: $B$ ... countable base |

==== Discussion ====
==== Parents ====
=== Subset of ===
[[Topological space]]
=== Requirements ===
[[Countable base for a topology]]