From d7809a884acefdd2d529b01cb5494a9d126857b5 Mon Sep 17 00:00:00 2001 From: Josia Pietsch Date: Wed, 7 Feb 2024 13:18:14 +0100 Subject: [PATCH] some changes --- inputs/lecture_15.tex | 4 ++++ inputs/lecture_16.tex | 11 ++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/inputs/lecture_15.tex b/inputs/lecture_15.tex index fa9c486..77a74ef 100644 --- a/inputs/lecture_15.tex +++ b/inputs/lecture_15.tex @@ -273,6 +273,7 @@ Recall: A limit of distal flows is distal. \end{proposition} \begin{proof} +\gist{% Let $(X,T)$ be a limit of $\Sigma = \{(X_i, T) : i \in I\}$. Suppose that each $(X_i, T)$ is distal. If $(X,T)$ was not distal, @@ -283,4 +284,7 @@ Recall: But then $g_n \pi_i(x_1) \to \pi_i(z)$ and $g_n \pi_i(x_2) \to \pi_i(z)$, which is a contradiction since $(X_i, T)$ is distal. +}{Suppose there is a proximal pair $x_1,x_2$. + Take $i$ such that $\pi_i(x_1) \neq \pi_i(x_2) \lightning$. +} \end{proof} diff --git a/inputs/lecture_16.tex b/inputs/lecture_16.tex index 075f78c..352277d 100644 --- a/inputs/lecture_16.tex +++ b/inputs/lecture_16.tex @@ -17,7 +17,7 @@ $X$ is always compact metrizable. % and $h\colon x \mapsto x + \alpha$.\footnote{Again $x + \alpha$ denotes $x \cdot \alpha$ in $\C$.} % \end{example} \begin{proof} - % TODO TODO TODO Think! +\gist{% The action of $1$ determines $h$. Consider \[ @@ -82,6 +82,15 @@ $X$ is always compact metrizable. For $\alpha = h$ we get that a flow $\Z \acts X$ corresponds to $\Z \acts K$ with $(1,x) \mapsto x + \alpha$. +}{ + \begin{itemize} + \item $G \coloneqq \overline{\{h^n : n \in \Z\} } \subseteq \cC(X,X)$. + \item $G$ is compact (Arzela-Ascoli), abelian topological group (closure of ab. top. group) + \item Take any $x \in G$. + \item $Gx$ is compact (since $g \mapsto gx$ is continuous and $G$ is compact) + \item Stabilizer $G_x$ is closed. $K \coloneqq \faktor{G}{G_x}$, $K \to X, fG_x \mapsto f(x)$. + \end{itemize} +} \end{proof} \begin{definition} Let $(X,T)$ be a flow