diff --git a/src/topology/main/interiorclosureboundary.tex b/src/topology/main/interiorclosureboundary.tex index c5af445..5209c2a 100644 --- a/src/topology/main/interiorclosureboundary.tex +++ b/src/topology/main/interiorclosureboundary.tex @@ -91,10 +91,16 @@ \begin{proposition} \label{proposition:separable-product} - Let $\seqf{X_j}$ be separable topological spaces, then $\prod_{j = 1}^n X_j$ is also separable. + Let $\seq{X_n}$ be separable topological spaces, then $\prod_{n \in \natp}X_n$ is separable. \end{proposition} \begin{proof} - Let $\seq{A_j}$ such that $A_j \subset X_j$ is countable and dense for each $1 \le j \le n$. By \autoref{proposition:dense-product}, $\prod_{j = 1}^n A_j$ is countable and dense in $\prod_{j = 1}^n X_j$. + For each $n \in \nat$, let $A_n \subset X_n$ be a countable dense subset. For each $N \in \nat$, let $B_N \subset X$ such that: + \begin{enumerate} + \item $B_N$ is countable. + \item For each $\bracsn{a_n}_1^N \subset \prod_{n = 1}^N A_n$, there exists $b \in B_N$ such that $a_n = b_n$ for all $1 \le j \le N$. + \end{enumerate} + + Then, $\bigcup_{N \in \natp}B_N$ is a countable dense subset of $\prod_{n \in \natp}X_n$. \end{proof}