Added section regarding the duality of L^p spaces.

This commit is contained in:
Bokuan Li
2026-06-15 21:47:49 -04:00
parent 35efec2d90
commit dadddc4663
6 changed files with 240 additions and 7 deletions

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@@ -352,7 +352,7 @@ A significant property of Hilbert spaces is that every closed subspace is comple
\phi_x: H \to \complex \quad \phi_x(y) = \dpn{y, x}{E}
\]
then the mapping $H \to H^*$ defined by $x \mapsto \phi_x$ is an isometric conjugate linear isomorphism.
then the mapping $H \to H^*$ defined by $x \mapsto \phi_x$ is an conjugate linear isometric isomorphism.
\end{theorem}
\begin{proof}
By the \hyperref[Cauchy-Schwarz inequality]{proposition:cauchy-schwarz} and definition of the norm, $x \mapsto \phi_x$ is an isometric conjugate linear map.

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@@ -6,7 +6,7 @@
Let $K \in \RC$ and $\dpn{E, F}{\lambda}$ be a duality of normed vector spaces over $K$ with $E$ being separable, then
\begin{enumerate}
\item The closed unit ball $S = \bracsn{y \in F|\ \norm{y}_{F} \le 1}$ is separable with respect to the $\sigma(F, E)$-topology.
\item If the duality is norming, then there exists $\seq{y_n} \subset F$ such that for each $x \in E$, $\norm{x}_E = \sup_{n \in \natp}\dpn{x, y_n}{\lambda}$.
\item If the duality is norming, then there exists $\seq{y_n} \subset F$ such that for each $x \in E$, $\norm{x}_E = \sup_{n \in \natp}|\dpn{x, y_n}{\lambda}|$.
\end{enumerate}
\end{proposition}
\begin{proof}