Tag: general-topology
- Prove that it is first countable
- The closest point to $x_0$ exists in a compact subset $K$
- A $\sigma$-compact but not hemicompact space
- Proof of Lemma 2.3 p.354 Massey
- Union of a locally finite collection of compact set is compact
- Intuition for homogeneous spaces
- Show this is a topological basis
- Does second countablity implies closed (or open) set in $X$ is a countable intersection of open sets in $X$
- In a metric space, is every open subset a non-redundant union of open balls
- Ideal topology on commutative ring