diff --git a/src/topology/main/c0.tex b/src/topology/main/c0.tex index 4b9571a..aee2e2c 100644 --- a/src/topology/main/c0.tex +++ b/src/topology/main/c0.tex @@ -13,7 +13,7 @@ Let $X$ be a topological space and $E$ be a TVS over $K \in \RC$, then: \begin{enumerate} \item $C_0(X; E) \subset BC(X; E)$. - \item $C_0(X; E)$ is a closed subspace of $BC(X; E)$ with respect to the uniform topology. + \item $C_0(X; E)$ is a closed subspace of $BC(X; E)$ with respect to the uniform topology. In particular, if $E$ is complete, then so is $C_0(X; E)$. \item If $X$ is a LCH space, then $C_c(X; E)$ is a dense subspace of $C_0(X; E)$ with respect to the uniform topology. \end{enumerate} \end{proposition} @@ -26,5 +26,15 @@ \[ f(\bracs{g \in V}) \subset (f - g)(X) + g(\bracs{g \in V}) \subset V + V = U \] + Thus $\bracs{f \not\in U}$ is a closed subset of $\bracs{g \not\in V}$, which is compact by \autoref{proposition:compact-extensions}. + + If $E$ is complete, then $BC(X; E)$ is complete by \autoref{definition:bounded-continuous-function-space}. Since $C_0(X; E)$ is a closed subspace, it is complete by \autoref{proposition:complete-closed}. + + (3): Let $f \in C_0(X; E)$ and $U \in \cn_E^o(0)$ be balanced. By \hyperref[Urysohn's Lemma]{lemma:lch-urysohn}, there exists $\phi \in C_c(X; [0, 1])$ such that $\phi|_{\bracs{f \not\in U}} = 1$. In which case, $\phi f \in C_c(X; E)$ with + \[ + (\phi f - f)(X) = \underbrace{(\phi f - f)(\bracs{f \not\in U})}_{0} + \underbrace{(\phi f - f)(\bracs{f \in U})}_{\in U} \in U + \] + + so $f \in \ol{C_c(X; E)}$. \end{proof} diff --git a/src/topology/main/index.tex b/src/topology/main/index.tex index a5ce394..9cda20e 100644 --- a/src/topology/main/index.tex +++ b/src/topology/main/index.tex @@ -21,4 +21,5 @@ \input{./para.tex} \input{./support.tex} \input{./lch.tex} +\input{./c0.tex} \input{./baire.tex}