\[
\newcommand{\C}{\mathbb{C}}
\newcommand{\cont}{\operatorname{\mathsf{C}}}
\newcommand{\haar}{\mathsf{m}}
\newcommand{\B}{\mathscr{B}}
\newcommand{\D}{\mathscr{D}}
\newcommand{\P}{\mathcal{P}}
\newcommand{\Q}{\mathbb{Q}}
\newcommand{\R}{\mathbb{R}}
\newcommand{\N}{\mathbb{N}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\sph}{\mathsf{S}^\mathsf{1}}
\newcommand{\g}{>}
\newcommand{\l}{<}
\newcommand{\intd}{\,\mathsf{d}}
\newcommand{\Re}{\mathsf{Re}}
\newcommand{\area}{\mathop{\mathsf{Area}}}
\newcommand{\met}{\mathop{\mathsf{d}}}
\newcommand{\emptyset}{\varnothing}
\DeclareMathOperator{\borel}{\mathsf{Bor}}
\DeclareMathOperator{\baire}{\mathsf{Baire}}
\newcommand{\orb}{\mathop{\mathsf{orb}}}
\newcommand{\symdiff}{\mathop\triangle}
\newcommand{\lp}[1][2]{\operatorname{\mathscr{L}^{\mathsf{#1}}}}
\newcommand{\Lp}[1][2]{\operatorname{\mathsf{L}^{\!\mathsf{#1}}}}
\]
Week 7 Coursework Test
- Give an example of a point $x \in \{0,1\}^\N$ for which
\[
\lim_{r \to \infty} \dfrac{1}{2^{2r}} \sum_{n=1}^{2^{2r}} x(n)
\qquad
\lim_{r \to \infty} \dfrac{1}{2^{2r+1}} \sum_{n=1}^{2^{2r+1}} x(n)
\]
both exist and are distinct.
- The strong law of large numbers states for the $(p,1-p)$ coin measure $\mu_p$ that the set
\[
F_p = \left\{ x \in \{0,1\}^\N : \lim_{N \to \infty} \dfrac{1}{N} \sum_{n=1}^N x(n) = p \right\}
\]
has measure 1.
- Prove that $p \ne q$ implies $F_p \cap F_q = \emptyset$.
- We have $\mu_p(X) = 1$ for all $0 \le p \le 1$. Briefly explain why there is no contradiction in writing $X$ as an uncountable union of sets $F_p$ each having measure 1.