From f613e65d10b7289971e2bb4edf4efce51c0d81e2 Mon Sep 17 00:00:00 2001 From: Bokuan Li Date: Tue, 7 Jul 2026 11:39:54 -0400 Subject: [PATCH] Removed parts from Zhu citations. --- src/dg/complex/entire.tex | 2 +- src/op/banach/invertible.tex | 2 +- src/op/banach/multiplicative.tex | 2 +- src/op/c-star/cont.tex | 2 +- src/op/c-star/gelfand.tex | 2 +- src/op/c-star/homomorphism.tex | 7 +++++++ src/op/c-star/order.tex | 2 +- src/op/c-star/sa.tex | 2 +- src/op/c-star/unitary.tex | 2 +- src/op/example/bc.tex | 2 +- src/topology/main/stonean.tex | 2 +- 11 files changed, 17 insertions(+), 10 deletions(-) diff --git a/src/dg/complex/entire.tex b/src/dg/complex/entire.tex index 90f0287..4bf3ea2 100644 --- a/src/dg/complex/entire.tex +++ b/src/dg/complex/entire.tex @@ -74,7 +74,7 @@ then $f = 1$. \end{proposition} -\begin{proof}[Proof, {{\cite[Lemma I.4.4]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Lemma 4.4]{Zhu}}}. ] By (c) and \autoref{proposition:entire-logarithm}, there exists $g \in H(\complex; \complex)$ such that $f = e^g$. Since $f(0) = 1$, $g(0) = 0$. As $f'(0) = g'(0)f(0) = 0$, $g'(0) = 0$ as well. From (c), $|g(z)| \le e^{|z|}$ for each $z \in \complex$. Thus for every $r > 0$ and $z \in B_\complex(0, r)$, $|g(z)| \le |g(z) - 2r|$, and diff --git a/src/op/banach/invertible.tex b/src/op/banach/invertible.tex index 320de3a..e8f9ab5 100644 --- a/src/op/banach/invertible.tex +++ b/src/op/banach/invertible.tex @@ -65,7 +65,7 @@ \label{proposition:swap-invertible} Let $A$ be a unital Banach algebra and $x, y \in A$, then $1 - xy \in G(A)$ if and only if $1 - yx \in G(A)$. \end{proposition} -\begin{proof}[Proof, {{\cite[Proposition I.3.4]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Proposition 3.4]{Zhu}}}. ] If $1 - xy \in G(A)$, then \begin{align*} (1 - yx)[y(1 - xy)^{-1}x + 1] &= y(1 - xy)^{-1}x + 1 \\ diff --git a/src/op/banach/multiplicative.tex b/src/op/banach/multiplicative.tex index d82de0f..e3c9090 100644 --- a/src/op/banach/multiplicative.tex +++ b/src/op/banach/multiplicative.tex @@ -69,7 +69,7 @@ \item $\phi(1) = 1$ and $\phi(G(A)) \subset \complex \setminus \bracs{0}$. \end{enumerate} \end{theorem} -\begin{proof}[Proof, {{\cite[Theorem I.4.5]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Theorem 4.5]{Zhu}}}. ] (1) $\Rightarrow$ (2): \autoref{proposition:multiplicative-unit}. (2) $\Rightarrow$ (1): Let $x \in A$ and $\lambda \in \complex$ with $|\lambda| > [x]_{sp}$, then $\lambda - x \in G(A)$ and $\phi(\lambda - x) \ne 0$. Therefore $\phi(x) \subset \ol{B(0, [x]_{sp})}$, and $\norm{\phi}_{A^*} = 1$. diff --git a/src/op/c-star/cont.tex b/src/op/c-star/cont.tex index 23b3628..6b47c67 100644 --- a/src/op/c-star/cont.tex +++ b/src/op/c-star/cont.tex @@ -136,7 +136,7 @@ \item $\norm{\Phi(x)}_B = \norm{x}_A$. \end{enumerate} \end{corollary} -\begin{proof}[Proof, {{\cite[II.10.7]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[10.7]{Zhu}}}. ] (1): Since $\Phi(G(A)) \subset G(B)$, $\sigma_B(\Phi(x)) \subset \sigma_A(x)$. If $\sigma_B(\Phi(x)) \subsetneq \sigma_A(x)$, then \hyperref[Urysohn's Lemma]{lemma:urysohn} implies that there exists $C(\sigma_A(x); \complex)$ such that $f|_{\sigma_B(\Phi(x))} = 0$ but $f \ne 0$. In which case, by (7) of the \hyperref[continuous functional calculus]{definition:continuous-functional-calculus}, $\Phi(f(x)) = f(\Phi(x)) = 0$, which contradicts the fact that $\Phi$ is injective. (2): By \autoref{corollary:c-star-unique-norm}, $\Phi$ is isometric. diff --git a/src/op/c-star/gelfand.tex b/src/op/c-star/gelfand.tex index 1e786d7..34daaed 100644 --- a/src/op/c-star/gelfand.tex +++ b/src/op/c-star/gelfand.tex @@ -10,7 +10,7 @@ is a unital $C^*$-isomorphism. \end{theorem} -\begin{proof}[Proof, {{\cite[Theorem II.9.4]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Theorem 9.4]{Zhu}}}. ] By construction $\Gamma_A$ is a unital algebra homomorphism. To see that $\Gamma_A$ preserves involutions, let $y \in A$ be self-adjoint. By \autoref{proposition:gelfand-transform-gymnastics} and \autoref{proposition:self-adjoint-spectrum}, $\Gamma_A(y)(\Omega(A)) = \sigma_A(y) \subset \real$, so $\Gamma_A(y) \in C(\Omega(A); \real)$. For any $x \in A$, write $x = \text{Re}(x) + i\text{Im}(x)$, where $\text{Re}(x)$ and $\text{Im}(x)$ are both self-adjoint, then diff --git a/src/op/c-star/homomorphism.tex b/src/op/c-star/homomorphism.tex index 3dfd820..429062f 100644 --- a/src/op/c-star/homomorphism.tex +++ b/src/op/c-star/homomorphism.tex @@ -36,4 +36,11 @@ \end{proof} +\begin{theorem} +\label{theorem:continuity-of-homomorphism-c-star} + Let $A, B$ be unital $C^*$-algebras and $\Phi: A \to B$ be a unital *-homomorphism, then $\Phi(A)$ is closed. +\end{theorem} +\begin{proof}[Proof, {{\cite[Theorem 11.1]{Zhu}}}. ] +\end{proof} + diff --git a/src/op/c-star/order.tex b/src/op/c-star/order.tex index fc50f4d..1ee0286 100644 --- a/src/op/c-star/order.tex +++ b/src/op/c-star/order.tex @@ -23,7 +23,7 @@ \item There exists $\lambda \ge \norm{x}_A$ such that $\norm{\lambda - x}_A \le \lambda$. \end{enumerate} \end{proposition} -\begin{proof}[Proof, {{\cite[Lemma II.11.3]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Lemma 11.3]{Zhu}}}. ] (1) $\Leftrightarrow$ (2): \autoref{proposition:positive-spectrum}. (2) $\Leftrightarrow$ (3): By assumption, $\sigma_A(x) \subset \real$, so \autoref{theorem:c-star-normal-spectral-radius} implies that diff --git a/src/op/c-star/sa.tex b/src/op/c-star/sa.tex index f1e8084..529e74c 100644 --- a/src/op/c-star/sa.tex +++ b/src/op/c-star/sa.tex @@ -35,7 +35,7 @@ \label{theorem:c-star-normal-spectral-radius} Let $A$ be a unital $C^*$-algebra and $x \in A$ be normal, then $\norm{x}_A = [x]_{sp}$. \end{theorem} -\begin{proof}[Proof, {{\cite[Theorem II.8.1]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Theorem 8.1]{Zhu}}}. ] First suppose that $x$ is self-adjoint. In this case, \begin{align*} \normn{x^2}_A &= \normn{xx^*}_A = \norm{x}_A^2 \\ diff --git a/src/op/c-star/unitary.tex b/src/op/c-star/unitary.tex index ab65824..abfe11c 100644 --- a/src/op/c-star/unitary.tex +++ b/src/op/c-star/unitary.tex @@ -42,7 +42,7 @@ \label{proposition:unitary-spectrum} Let $A$ be a unital $C^*$-algebra and $x \in A$ be unitary, then $\sigma_A(x) \subset \partial B_\complex(0, 1)$. \end{proposition} -\begin{proof}[Proof, {{\cite[Proposition II.8.2]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Proposition 8.2]{Zhu}}}. ] By \autoref{lemma:unitary-unit}, $\norm{x}_A = 1$, so $\sigma_A(x) \subset \ol{B_\complex(0, 1)}$. Thus \[ \bracsn{\ol{\lambda}|\lambda \in \sigma_A(x)} = \sigma_A(x^*) = \sigma_A(x^{-1}) \subset \ol{\complex \setminus B_\complex(0, 1)} diff --git a/src/op/example/bc.tex b/src/op/example/bc.tex index 3365285..32e3b7a 100644 --- a/src/op/example/bc.tex +++ b/src/op/example/bc.tex @@ -17,7 +17,7 @@ is a homeomorphism. Under the identification $\beta X = \Omega(BC(X; \complex))$, $\Gamma_{BC(X; \complex)} = \beta$. \end{theorem} -\begin{proof}[Proof, {{\cite[Theorem I.6.4]{Zhu}}}. ] +\begin{proof}[Proof, {{\cite[Theorem 6.4]{Zhu}}}. ] Let $\phi \in BC(X; \complex)^* \setminus \ol{E(X)}$, then there exists $\seqf{f_k} \subset BC(X; \complex)$ and $\eps > 0$ such that for every $x \in X$, \[ f(x) = \sum_{k = 1}^n |f_k(x) - \dpn{f_k, \phi}{BC(X; \complex)}|^2 \ge \eps^2 diff --git a/src/topology/main/stonean.tex b/src/topology/main/stonean.tex index b716e03..0871b1d 100644 --- a/src/topology/main/stonean.tex +++ b/src/topology/main/stonean.tex @@ -40,7 +40,7 @@ so $g \le F$. As this holds for all upper bounds of $\cf$, $g$ is the supremum of $\cf$ in $C(X; \real)$. - ($\Leftarrow$, \cite[Theorem II.9.6]{Zhu}): Suppose that $X$ is completely regular and $C(X; \real)$ is order complete. Let $U \subset X$ be open and + ($\Leftarrow$, \cite[Theorem 9.6]{Zhu}): Suppose that $X$ is completely regular and $C(X; \real)$ is order complete. Let $U \subset X$ be open and \[ \cf = \bracs{f \in C(X; [0, 1])| 0 \le f \le \one_U} \]