diff --git a/presentation/ZheyuanWu_HonorThesis_Presentation.pdf b/presentation/ZheyuanWu_HonorThesis_Presentation.pdf index 2066138..d8b1fb8 100644 Binary files a/presentation/ZheyuanWu_HonorThesis_Presentation.pdf and b/presentation/ZheyuanWu_HonorThesis_Presentation.pdf differ diff --git a/presentation/ZheyuanWu_HonorThesis_Presentation.tex b/presentation/ZheyuanWu_HonorThesis_Presentation.tex index 3b1f33f..fac8934 100644 --- a/presentation/ZheyuanWu_HonorThesis_Presentation.tex +++ b/presentation/ZheyuanWu_HonorThesis_Presentation.tex @@ -538,26 +538,56 @@ \section{Geometry of State Space} - -\begin{frame}{Observable Diameter} - \begin{block}{Definition} - For a metric-measure space $X$ and $\kappa>0$, +\begin{frame}{Observable diameter: the inner definition} + \begin{block}{Partial diameter on $\mathbb{R}$} + Let $\nu$ be a Borel probability measure on $\mathbb{R}$ and let $\alpha \in (0,1]$. + The \textbf{partial diameter} of $\nu$ at mass level $\alpha$ is $$ - \obdiam_{\mathbb{R}}(X;-\kappa) - = - \sup_{f\in \operatorname{Lip}_1(X,\mathbb{R})} - \diameter(f_*\mu_X;1-\kappa). + \diameter(\nu;\alpha):= + \{\diameter(A):A \subseteq \mathcal{B}(\mathbb{R}), + \nu(A)\ge \alpha + \}, + $$ + where + $$ + \diameter(A):=\sup_{x,y\in A}|x-y|. $$ \end{block} + \vspace{0.4em} \begin{itemize} - \item It asks how concentrated every $1$-Lipschitz real observable must be. - \item In the thesis, entropy is used as a concrete observable-diameter proxy. - \item Hopf fibration lets us compare $\mathbb{C}P^n$ with spheres. + \item This asks for the shortest interval-like region containing at least $\alpha$ of the total mass. + \item So $\diameter(\nu;1-\kappa)$ measures how tightly we can capture \emph{most} of the distribution, allowing us to discard a set of mass at most $\kappa$. \end{itemize} + +\end{frame} + +\begin{frame}{Observable diameter of a metric-measure space} + \begin{block}{Definition} + Let $X=(X,d_X,\mu_X)$ be a metric-measure space and let $\kappa>0$. + The \textbf{observable diameter} of $X$ is + $$ + \obdiam_{\mathbb{R}}(X;-\kappa) + := + \sup_{f\in \operatorname{Lip}_1(X,\mathbb{R})} + \diameter(f_*\mu_X;1-\kappa), + $$ + where $\operatorname{Lip}_1(X,\mathbb{R})$ is the set of all $1$-Lipschitz functions + $f:X\to\mathbb{R}$, and $f_*\mu_X$ is the pushforward measure on $\mathbb{R}$. + \end{block} + + \vspace{0.4em} + \begin{itemize} + \item Each $1$-Lipschitz function $f$ is viewed as an \textbf{observable} on $X$. + \item The pushforward measure $f_*\mu_X$ is the distribution of the values of that observable. + \item If $\obdiam_{\mathbb{R}}(X;-\kappa)$ is small, then \emph{every} $1$-Lipschitz observable is strongly concentrated. + \end{itemize} + \end{frame} \begin{frame}{A Geometric Consequence} + In this thesis, entropy functions are used as concrete observables to estimate observable diameter, and the Hopf fibration helps transfer information between $S^{2n+1}$ and $\mathbb{C}P^n$. + \vspace{0.4em} \begin{block}{Projective-space estimate} For $0<\kappa<1$, $$