Second-Countable Space is First-Countable/Proof 2
Jump to navigation
Jump to search
Theorem
Let $T = \struct {S, \tau}$ be a topological space which is second-countable.
Then $T$ is also first-countable.
Proof
By definition of second-countable space, there exists a countable analytic basis $\BB \subseteq \tau$.
Then each $x \in S$ has a countable local basis:
- $\BB_x := \set {U \in \BB: x \in U}$
$\blacksquare$
![]() | Although this article appears correct, it's inelegant. There has to be a better way of doing it. In particular: details You can help $\mathsf{Pr} \infty \mathsf{fWiki}$ by redesigning it. To discuss this page in more detail, feel free to use the talk page. When this work has been completed, you may remove this instance of {{Improve}} from the code.If you would welcome a second opinion as to whether your work is correct, add a call to {{Proofread}} the page. |