diff --git a/inputs/lecture_23.tex b/inputs/lecture_23.tex index 1ecc0ac..df324e6 100644 --- a/inputs/lecture_23.tex +++ b/inputs/lecture_23.tex @@ -1,8 +1,8 @@ -\lecture{23}{2023-07-06}{} -\section{Recap} -In this lecture we will recall the most important point from the lecture. +\lecture{23}{2023-07-06}{Recap} +\subsection{Recap} +In this lecture we recall the most important point from the lecture. -\subsection{Construction of iid random variables.} +\subsubsection{Construction of iid random variables.} \begin{itemize} \item Definition of a consistent family (\autoref{def:consistentfamily}) @@ -20,20 +20,18 @@ In this lecture we will recall the most important point from the lecture. (\autoref{thm:kolmogorovconsistency}) \end{itemize} -\subsection{Limit theorems} +\subsubsection{Limit theorems} \begin{itemize} \item Work with iid.~random variables. \item Notions of convergence (\autoref{def:convergence}) \item Implications between different notions of convergence (very important) and counter examples. (\autoref{thm:convergenceimplications}) - \item \begin{itemize} - \item Laws of large numbers: (\autoref{lln}) + \item \item Laws of large numbers: (\autoref{lln}) \begin{itemize} \item WLLN: convergence in probability \item SLLN: weak convergence \end{itemize} - \end{itemize} \item \autoref{thm2} (building block for SLLN): Let $(X_n)$ be independent with mean $0$ and $\sum \sigma_n^2 < \infty$, then $ \sum X_n $ converges a.s. @@ -58,7 +56,7 @@ In this lecture we will recall the most important point from the lecture. \end{itemize} \end{itemize} -\subsubsection{Fourier transform / characteristic functions / weak convegence} +\subsubsubsection{Fourier transform / characteristic functions / weak convegence} \begin{itemize} \item Definition of Fourier transform @@ -101,13 +99,13 @@ In this lecture we will recall the most important point from the lecture. \paragraph{Convolution} \begin{itemize} \item Definition of convolution. - \todo{Copy from exercise sheet and write a section about this} + \todo{Copy from exercise sheet and write a subsection about this} \item $X_i \sim \mu_i \text{ iid. }\implies X_1 + \ldots + X_n \sim \mu_1 \ast \ldots \ast \mu_n$. \end{itemize} -\subsubsection{CLT} +\subsubsubsection{CLT} \begin{itemize} \item Statement of the CLT \item Several versions: @@ -119,7 +117,7 @@ In this lecture we will recall the most important point from the lecture. \item How to apply this? Exercises! \end{itemize} -\subsection{Conditional expectation} +\subsubsection{Conditional expectation} \begin{itemize} \item Definition and existence of conditional expectation for $X \in L^1(\Omega, \cF, \bP)$ \item If $H = L^2(\Omega, \cF, \bP)$, then $\bE[ \cdot | \cG]$ @@ -130,7 +128,7 @@ In this lecture we will recall the most important point from the lecture. Singularity in this context? % TODO \end{itemize} -\subsection{Martingales} +\subsubsection{Martingales} \begin{itemize} \item Definition of Martingales @@ -154,7 +152,7 @@ In this lecture we will recall the most important point from the lecture. \end{itemize} -\subsection{Markov Chains} +\subsubsection{Markov Chains} \begin{itemize} \item What are Markov chains? diff --git a/inputs/prerequisites.tex b/inputs/prerequisites.tex index 4777387..c092688 100644 --- a/inputs/prerequisites.tex +++ b/inputs/prerequisites.tex @@ -73,7 +73,9 @@ from the lecture on stochastic. \begin{subproof} We have $\bE[|X_n - X|] \to 0$. Suppose there exists an $\epsilon > 0$ such that - $\lim_{n \to \infty} \bP[|X_n - X| > \epsilon] = c > 0$. + $\limsup\limits_{n \to \infty} \bP[|X_n - X| > \epsilon] = c > 0$. + W.l.o.g.~$\lim_{n \to \infty} \bP[|X_n - X| > \epsilon] = c$, + otherwise choose an appropriate subsequence. We have \begin{IEEEeqnarray*}{rCl} \bE[|X_n - X|] &=& \int_\Omega |X_n - X | d\bP\\ @@ -90,7 +92,7 @@ from the lecture on stochastic. $X_n \xrightarrow{\bP} X \notimplies X_n\xrightarrow{L^1} X$ \end{claim} \begin{subproof} - Take $([0,1], \cB([0,1 ]), \lambda)([0,1], \cB([0,1 ]), \lambda)$ + Take $([0,1], \cB([0,1 ]), \lambda)$ and define $X_n \coloneqq n \One_{[0, \frac{1}{n}]}$. We have $\bP[|X_n| > \epsilon] = \frac{1}{n}$ for $n$ large enough.