diff --git a/.vscode/project.code-snippets b/.vscode/project.code-snippets index acf01f3..6500efa 100644 --- a/.vscode/project.code-snippets +++ b/.vscode/project.code-snippets @@ -137,6 +137,11 @@ "prefix": "cal", "body": ["\\mathcal{$1}$0"] }, + "Mathscr": { + "scope": "latex", + "prefix": "scr", + "body": ["\\mathscr{$1}$0"] + }, "Mathfrak": { "scope": "latex", "prefix": "fk", diff --git a/src/fa/lc/bornologic.tex b/src/fa/lc/bornologic.tex index c8dbb6d..0341051 100644 --- a/src/fa/lc/bornologic.tex +++ b/src/fa/lc/bornologic.tex @@ -1,15 +1,15 @@ -\section{Bornologic Spaces} -\label{section:bornologic} +\section{Bornological Spaces} +\label{section:bornological} -\begin{definition}[Bornologic Space] -\label{definition:bornologic-space} +\begin{definition}[Bornological Space] +\label{definition:bornological-space} Let $E$ be a locally convex space, then the following are equivalent: \begin{enumerate} \item For any $U \subset E$ convex and balanced, if $U$ absorbs every bounded set of $E$, then $U \in \cn_E(0)$. \item For any seminorm $\rho: E \to [0, \infty)$ that is bounded on all bounded sets of $E$, $\rho$ is continuous. \end{enumerate} - If the above holds, then $E$ is a \textbf{bornologic space}. + If the above holds, then $E$ is a \textbf{bornological space}. \end{definition} \begin{proof} (1) $\Rightarrow$ (2): Let $B \subset E$ be bounded, then there exists $R > 0$ such that $\rho(B) \subset [0, R)$. In which case, @@ -23,8 +23,8 @@ \end{proof} \begin{proposition} -\label{proposition:bornologic-bounded} - Let $E$ be a bornologic space, $F$ be a locally convex space, and $T \in \hom(E; F)$, then the following are equivalent: +\label{proposition:bornological-bounded} + Let $E$ be a bornological space, $F$ be a locally convex space, and $T \in \hom(E; F)$, then the following are equivalent: \begin{enumerate} \item $T$ is continuous. \item $T$ is sequentially continuous. @@ -34,32 +34,57 @@ \begin{proof} (2) $\Rightarrow$ (3): Let $B \subset E$ be a bounded set, $\seq{x_n} \subset E$, and $\seq{\lambda_n} \subset K$ such that $\lambda_n \to 0$ as $n \to \infty$, then $\lambda_n x_n \to 0$ as $n \to \infty$. By sequential continuity of $T$, $T(\lambda_n x_n) \to 0$ as $n \to \infty$ as well. Thus $T(B)$ is also bounded. - (3) $\Rightarrow$ (1): Let $\rho: F \to [0, \infty)$ be a continuous seminorm, then $\rho \circ T$ is a seminorm on $E$ that is bounded on bounded sets. Since $E$ is bornologic, $\rho \circ T$ is continuous. Therefore $T$ is continuous by \autoref{proposition:tvs-convex-morphism}. + (3) $\Rightarrow$ (1): Let $\rho: F \to [0, \infty)$ be a continuous seminorm, then $\rho \circ T$ is a seminorm on $E$ that is bounded on bounded sets. Since $E$ is bornological, $\rho \circ T$ is continuous. Therefore $T$ is continuous by \autoref{proposition:tvs-convex-morphism}. \end{proof} \begin{proposition} -\label{proposition:metrisable-bornologic} - Let $E$ be a metrisable locally convex space, then $E$ is bornologic. +\label{proposition:metrisable-bornological} + Let $E$ be a metrisable locally convex space, then $E$ is bornological. \end{proposition} \begin{proof} - Let $U \subset E$ be convex and balanced such that $U$ absorbs every bounded set of $E$. Let $\seq{U_n} \subset \cn^o(0)$ be a decreasing countable fundamental system of neighbourhoods at $0$. If $U_n \setminus nA \ne \emptyset$ for all $n \in \natp$, then there exists $\seq{x_n}$ such that $x_n \in U_n \setminus nA$ for all $n \in \natp$. In which case, $x_n \to 0$ as $n \to \infty$, so $\seq{x_n}$ is bounded. By assumption, there exists $n \in\natp$ such that $nA \supset \seq{x_n}$, which contradicts the fact that $\seq{x_n} \cap A = \emptyset$. + Let $A \subset E$ be a convex and circled set that absorbs every bounded set of $E$, and $\seq{U_n} \subset \cn_E(0)$ be a decreasing fundamental system of neighbourhoods at $0$. If $A \not\in \cn_E(0)$, then $U_n \setminus nA \ne \emptyset$ for all $n \in \natp$. For each $n \in \natp$, let $x_n \in U_n \setminus nA$, then $x_n \to 0$ as $n \to \infty$, and $\seq{x_n}$ is bounded. However, since $A$ absorbs every bounded set of $E$, there exists $n \in \natp$ such that $nA \supset \seq{x_n}$, which contradicts the assumption that $A \not\in \cn_E(0)$. \end{proof} \begin{proposition} -\label{proposition:bornologic-limit} - Let $\seqi{E}$ be bornologic spaces over $K \in \RC$, $E$ be a vector space over $K$, and $\seqi{T}$ such that $T_i \in \hom(E_i; E)$ for all $i \in I$, then $E$ equipped with the inductive topology is bornolgic. +\label{proposition:bornological-limit} + Let $\seqi{E}$ be bornological spaces over $K \in \RC$, $E$ be a vector space over $K$, and $\seqi{T}$ such that $T_i \in \hom(E_i; E)$ for all $i \in I$, then $E$ equipped with the inductive topology is bornolgic. \end{proposition} \begin{proof} - Let $\rho: E \to [0, \infty)$ be a seminorm on $E$ that is bounded on all bounded sets. For each $i \in I$ and $B \subset E_i$ bounded, $T_i(B)$ is bounded by \autoref{proposition:bornologic-bounded}, and $\rho \circ T_i(B)$ is bounded by assumption. Thus for every $i \in I$, $\rho \circ T_i$ is continuous, so $\rho$ is continuous by (4) of \autoref{definition:lc-inductive}. + Let $\rho: E \to [0, \infty)$ be a seminorm on $E$ that is bounded on all bounded sets. For each $i \in I$ and $B \subset E_i$ bounded, $T_i(B)$ is bounded by \autoref{proposition:bornological-bounded}, and $\rho \circ T_i(B)$ is bounded by assumption. Thus for every $i \in I$, $\rho \circ T_i$ is continuous, so $\rho$ is continuous by (4) of \autoref{definition:lc-inductive}. \end{proof} \begin{proposition} -\label{proposition:bornologic-continuous-complete} - Let $E$ be a bornologic space and $F$ be a complete separated locally convex space, then $L_b(E; F)$ is complete. In particular, $E^*$ equipped with the topology of bounded convergence is complete. +\label{proposition:bornological-continuous-complete} + Let $E$ be a bornological space and $F$ be a complete separated locally convex space, then $L_b(E; F)$ is complete. In particular, $E^*$ equipped with the topology of bounded convergence is complete. \end{proposition} \begin{proof} - By \autoref{proposition:bornologic-bounded}, $L_b(E; F) = B(E; F)$. By \autoref{proposition:operator-space-completeness}, $B(E; F)$ is complete, so $L_b(E; F)$ is complete as well. + By \autoref{proposition:bornological-bounded}, $L_b(E; F) = B(E; F)$. By \autoref{proposition:operator-space-completeness}, $B(E; F)$ is complete, so $L_b(E; F)$ is complete as well. \end{proof} +\begin{definition}[Associated Bornological Space] +\label{definition:associated-bornological} + Let $(E, \mathcal{T})$ be a separated locally convex space over $K \in \RC$, then there exists a locally convex topology $\mathcal{T}_B \subset 2^E$ such that: + \begin{enumerate} + \item $B(E, \mathcal{T}_B) \supset B(E, \mathcal{T})$. + \item[(U)] For every $\mathcal{S}$ satisfying (1), $\mathcal{S} \subset \mathcal{T}_B$. In particular, $\mathcal{T} \subset \mathcal{T}_B$ and $B(E, \mathcal{T}_B) = B(E, \mathcal{T})$. + \item $(E, \mathcal{T}_B)$ is a bornological space. + \item Let $\mathcal{B} \subset B(E, \topo)$ be the collection of all convex, circled, bounded, and closed subsets of $E$, ordered by inclusion. For each $B \in \mathcal{B}$, let $(E_B, \rho_B)$ be the normed space associated with $B$ and $\iota_B: E_B \to E$ be the canonical inclusion, then $\mathcal{T}_B$ is the inductive topology induced by $\bracsn{\iota_B}_{B \in \mathcal{B}}$. + \end{enumerate} + + The space $(E, \mathcal{T}_B)$ is the \textbf{bornological space associated with} $E$. +\end{definition} +\begin{proof} + Let $\mathscr{T}$ be the collection of all topologies satisfying (1), then $\mathcal{T} \in \mathscr{T}$, so $\mathscr{T} \ne \emptyset$. Let $\mathcal{T}_B$ be the projective topology induced by $\mathscr{T}$. + + (1): Since $\mathcal{T}_B \supset \mathcal{T}$, $B(E, \mathcal{T}) \supset B(E, \mathcal{T}_B)$. Let $B \in (E, \mathcal{T})$ and $U \in \cn_{\mathcal{T}_B}(0)$, then there exists $\mathscr{S} \subset \mathscr{T}$ finite and $\bracsn{U_{\mathcal{S}}}_{\mathcal{S} \in \mathscr{S}}$ such that $\bigcap_{\mathcal{S} \in \mathscr{S}}U_{\mathcal{S}} \subset U$. In which case, since $B(E, \mathcal{T}) = B(E, \mathcal{S})$ for all $\mathcal{S} \in \mathscr{S}$, $\bigcap_{\mathcal{S} \in \mathscr{S}}U_{\mathcal{S}}$ absorbs $B$, so $U$ absorbs $B$ as well. + + (U): By (U) of the \hyperref[projective topology]{definition:tvs-initial}. + + (3): Let $\rho: E \to [0, \infty)$ be a seminorm that is bounded on bounded sets, then the topology induced by $\rho$ satisfies (1). By (U), $\rho$ is continuous with respect to $\mathcal{T}_B$, so $(E, \mathcal{T}_B)$ is a bornological space. + + (4): Let $\mathcal{S}$ be the inductive topology on $E$ induced by $\bracsn{\iota_B}_{B \in \mathcal{B}}$. Let $B \in B(E, \mathcal{T})$, $U \in \cn_{\mathcal{S}}(0)$, and $\rho: E \to [0, \infty)$ be the gauge of $U$. Since $\iota_{\ol B} \in L(E_{\ol B}; E, \mathcal{S})$, there exists $\lambda > 0$ such that $\rho \le \lambda \iota_{\ol B} \circ \rho_{\ol B}$. Thus $2\lambda U \supset B$ and $(E, \mathcal{S})$ satisfies (1). By (U), $\mathcal{T}_B \supset \mathcal{S}$. + + On the other hand, since $B(E, \mathcal{T}_B) = B(E, \mathcal{T})$, for each $B \in \mathcal{B}$, $\iota_B: E_B \to (E, \mathcal{T}_B)$ is continuous. Therefore by (U) of the \hyperref[inductive topology]{definition:lc-inductive}, $\mathcal{S} \supset \mathcal{T}_B$. +\end{proof} diff --git a/src/fa/lc/convex.tex b/src/fa/lc/convex.tex index 15a7af3..a17c58d 100644 --- a/src/fa/lc/convex.tex +++ b/src/fa/lc/convex.tex @@ -199,3 +199,32 @@ $(3) \Rightarrow (1)$: For each $i \in I$ and $r > 0$, $\bracs{x \in E| [x]_i < r}$ is convex. \end{proof} + + + +\begin{definition}[Associated Normed Space] +\label{definition:lc-associated-normed-space} + Let $E$ be a separated locally convex space and $A \subset E$ be convex and circled. Let $E_0 = \bigcup_{n \in \natp}nA$, $\rho_0: E_0 \to [0, \infty)$ be the gauge of $A$, and $(E_A, \rho_A)$ be the quotient of $E_0$ by $\bracs{\phi = 0}$, equipped with the quotient norm of $\rho_0$, then + \begin{enumerate} + \item $(E_A, \rho_A)$ is a normed space. + \end{enumerate} + + If $A$ is radial, then $E_0 = E$ and the map $\pi_A: E \to E_A$ is the \textbf{canonical projection}, and + \begin{enumerate}[start=1] + \item If $A \in \cn_E(0)$, then $\pi_A \in L(E; E_A)$. + \end{enumerate} + + If $(E_0, \rho_0)$ is separated, then $(E_0, \rho_0) = (E_A, \rho_A)$, and the map $\iota_A: E_A \to E$ is the \textbf{canonical inclusion}. In particular, if $A$ is bounded, then + \begin{enumerate}[start=2] + \item $(E_0, \rho_0)$ is separated. + \item $\iota_A \in L(E_A; E)$. + \end{enumerate} + + The space $(E_A, \rho_A)$ is the \textbf{normed space associated with} $A$. +\end{definition} +\begin{proof} + (3): Let $x \in E_0 \setminus \bracs{0}$. Since $E$ is separated, there exists $U \in \cn_E(0)$ such that $x \not\in U$. As $A$ is bounded, there exists $\lambda > 0$ such that $\lambda U \supset A$. In which case, $x \not\in \lambda^{-1}A$, and $E_0$ is separated. + + (4): Let $U \in \cn_E(0)$, then there exists $\lambda > 0$ such that $\lambda U \supset A$, so $\iota_A^{-1}(U) \supset \lambda^{-1}A \in \cn_{E_A}(0)$, and $\iota_A$ is continuous by \autoref{proposition:tvs-convex-morphism}. +\end{proof} + diff --git a/src/fa/tvs/bounded.tex b/src/fa/tvs/bounded.tex index f5d0b63..dba1c91 100644 --- a/src/fa/tvs/bounded.tex +++ b/src/fa/tvs/bounded.tex @@ -3,13 +3,13 @@ \begin{definition}[Bounded] \label{definition:bounded} - Let $E$ be a TVS over $K \in \RC$ and $B \subset E$, then the following are equivalent: + Let $(E, \topo)$ be a TVS over $K \in \RC$ and $B \subset E$, then the following are equivalent: \begin{enumerate} \item For every $U \in \cn(0)$, there exists $\lambda \in K$ such that $\lambda U \supset B$. \item For every $\seq{x_n} \subset B$ and $\seq{\lambda_n} \subset K$ such that $\lambda_n \to 0$, $\lambda_n x_n \to 0$ as $n \to \infty$. \end{enumerate} - If the above holds, then $B$ is \textbf{bounded}. The collection $B(E)$ is the set of all bounded sets of $E$. + If the above holds, then $B$ is \textbf{bounded}. The collection $B(E) = B(E, \topo)$ is the set of all bounded sets of $E$. \end{definition} \begin{proof} (1) $\Rightarrow$ (2): Let $U \in \cn_E(0)$ be circled, then there exists $k \in \natp$ such that $kU \supset B$. Since $\lambda_n \to 0$ as $n \to \infty$, there exists $N \in \natp$ such that $|\lambda_n| \le 1/k$ for all $n \ge N$. In which case, $\lambda_n x_n \in \lambda_n B \subset U$ for all $n \ge N$. diff --git a/src/fa/tvs/complete-metric.tex b/src/fa/tvs/complete-metric.tex index c463a11..ced164c 100644 --- a/src/fa/tvs/complete-metric.tex +++ b/src/fa/tvs/complete-metric.tex @@ -111,7 +111,7 @@ \end{enumerate} \end{theorem} \begin{proof} - Suppose that $T(E)$ is not meagre. Let $r_0 > 0$ and $r > 0$ such that $B_E(0, r) + B_E(0, r) \subset B_E(0, r_0)$, then since $B_E(0, r)$ is absorbing, + Suppose that $T(E)$ is not meagre. Let $r_0 > 0$ and $r > 0$ such that $B_E(0, r) + B_E(0, r) \subset B_E(0, r_0)$, then since $B_E(0, r)$ is radial, \[ E = \bigcup_{n \in \natp}nB_E(0, r) \quad \overline{T(E)} = \bigcup_{n \in \natp}\overline{nT(B_E(0, r))} \] diff --git a/src/fa/tvs/definition.tex b/src/fa/tvs/definition.tex index 84cef6c..ef6e95a 100644 --- a/src/fa/tvs/definition.tex +++ b/src/fa/tvs/definition.tex @@ -137,7 +137,7 @@ \label{proposition:tvs-good-neighbourhood-base} Let $E$ be a topological vector space over $K \in \RC$, then \begin{enumerate} - \item $E$ admits a fundamental system of neighbourhoods at $0$ consisting of circled and absorbing sets. + \item $E$ admits a fundamental system of neighbourhoods at $0$ consisting of circled and radial sets. \item The fundamental system of neighbourhoods in $(1)$ can be taken to be open or closed. \end{enumerate} \end{proposition} diff --git a/src/fa/tvs/projective.tex b/src/fa/tvs/projective.tex index b17d8a6..98c5405 100644 --- a/src/fa/tvs/projective.tex +++ b/src/fa/tvs/projective.tex @@ -20,6 +20,7 @@ is a fundamental system of neighbourhoods for $E$ at $0$. \end{enumerate} + The uniformity $\fU$ and its topology are the \textbf{projective uniformity/topology} induced by $\seqi{T}$. \end{definition} \begin{proof} diff --git a/src/measure/vector/vector.tex b/src/measure/vector/vector.tex index 3957531..89cb6c5 100644 --- a/src/measure/vector/vector.tex +++ b/src/measure/vector/vector.tex @@ -34,7 +34,7 @@ \sup_{A \in \cm}|\dpn{\phi, x_A}{E^{**}}| = \sup_{A \in \cm}|\dpn{\mu(A),\phi}{E}| < \infty \] - By \autoref{proposition:bornologic-continuous-complete} and \autoref{proposition:metrisable-bornologic}, $E^*$ is a Banach space. The \hyperref[Uniform Boundedness Principle]{theorem:uniform-boundedness} implies that + By \autoref{proposition:bornological-continuous-complete} and \autoref{proposition:metrisable-bornological}, $E^*$ is a Banach space. The \hyperref[Uniform Boundedness Principle]{theorem:uniform-boundedness} implies that \[ \sup_{A \in \cm}\norm{\mu(A)}_{E} = \sup_{A \in \cm}\norm{x_A}_{E^{**}} < \infty \]