Changeset - b554f1fbc443
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Andras Gilyen - 8 years ago 2017-09-08 17:09:07
gilyen@clayoquot.swat.cwi.nl
Incr.
1 file changed with 5 insertions and 3 deletions:
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main.tex
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@@ -17,96 +17,98 @@
 

	
 
\usepackage{tikz}
 
\usepackage{amssymb}
 
\usepackage{mathtools}
 
\usepackage{bm}
 
\usepackage{bbm}
 
%\usepackage{bbold}
 
\usepackage{verbatim}
 

	
 
%for correcting large brackets spacing
 
\usepackage{mleftright}\mleftright
 

	
 
\usepackage{algorithm}
 
\usepackage{algorithmic}
 
\usepackage{enumitem}
 
\usepackage{float}
 

	
 
%\usepackage{titling}
 

	
 
%\setlength{\droptitle}{-5mm}  
 

	
 
%\usepackage{MnSymbol}
 
\newcommand{\cupdot}{\overset{.}{\cup}}
 
\newcommand{\pvp}{\vec{p}{\kern 0.45mm}'}
 

	
 
\DeclarePairedDelimiter\bra{\langle}{\rvert}
 
\DeclarePairedDelimiter\ket{\lvert}{\rangle}
 
\DeclarePairedDelimiterX\braket[2]{\langle}{\rangle}{#1 \delimsize\vert #2}
 
\newcommand{\underflow}[2]{\underset{\kern-60mm \overbrace{#1} \kern-60mm}{#2}}
 

	
 
\def\Ind(#1){{{\tt Ind}({#1})}}
 
\def\Id{\mathrm{Id}}
 
\def\Pr{\mathrm{Pr}}
 
\def\Tr{\mathrm{Tr}}
 
\def\im{\mathrm{im}}
 
\newcommand{\bOt}[1]{\widetilde{\mathcal O}\left(#1\right)}
 
\newcommand{\bigO}[1]{\mathcal O\left(#1\right)}
 
\newcommand{\Res}[1]{\#\mathrm{Res}\left(#1\right)}
 

	
 
\newcommand{\QMAo}{\textsf{QMA$_1$}}
 
\newcommand{\BQP}{\textsf{BQP}}
 
\newcommand{\NP}{\textsf{NP}}
 
\newcommand{\SharpP}{\textsf{\# P}}
 

	
 
\newcommand{\diam}[1]{\mathcal{D}\left(#1\right)}
 
\newcommand{\paths}[1]{\mathcal{P}\left(#1\to\mathbf{1}\right)}
 
\newcommand{\start}[1]{\textsc{start}\left(#1\right)}
 
\newcommand{\initone}[1]{\textsc{InitOne}\left(#1\right)}
 
\newcommand{\patch}[1]{\textsc{Patch}\left(#1\right)}
 
\newcommand{\patches}[1]{\textsc{Patches}\left(#1\right)}
 
\newcommand{\maxgap}[1]{\mathrm{maxgap}\left(#1\right)}
 
\newcommand{\gaps}[1]{#1_{\mathrm{gaps}}}
 
\renewcommand{\P}{\mathbb{P}}
 
\newcommand{\E}{\mathbb{E}}
 
\newcommand{\NZ}[1]{\mathrm{NZ}^{(#1)}}
 
\newcommand{\Z}[1]{\mathrm{Z}^{(#1)}}
 
%\newcommand{\dist}[1]{d_{\!\!\not\,#1}}
 
\newcommand{\dist}[1]{d_{\neg #1}}
 

	
 
\newcommand{\todo}[1]{{\color{red}\textbf{TODO:} #1}}
 

	
 
\long\def\ignore#1{}
 

	
 
\newtheorem{theorem}{Theorem}
 
\newtheorem{corollary}[theorem]{Corollary}%[theorem]
 
\newtheorem{lemma}[theorem]{Lemma}
 
\newtheorem{prop}[theorem]{Proposition}
 
\newtheorem{definition}[theorem]{Definition}
 
\newtheorem{claim}[theorem]{Claim}
 
\newtheorem{remark}[theorem]{Remark}
 

	
 
\newenvironment{proof}
 
{\noindent {\bf Proof. }}
 
{{\hfill $\Box$}\\	\smallskip}
 

	
 
\usepackage[final]{hyperref}
 
\hypersetup{
 
	colorlinks = true,
 
	allcolors = {blue},
 
}
 
\usepackage{ifpdf} 
 
\ifpdf
 
	\typeout{^^J *** PDF mode *** } 
 
%	\input{myBiblatex.tex}
 
%	\addbibresource{LLL.bib}	
 
%\else
 
%	\typeout{^^J *** DVI mode ***} 
 
%	\hypersetup{breaklinks = true}
 
%	\usepackage[quadpoints=false]{hypdvips}
 
	\let\oldthebibliography=\thebibliography
 
	\let\endoldthebibliography=\endthebibliography
 
	\renewenvironment{thebibliography}[1]{%
 
		\begin{oldthebibliography}{#1}%
 
			\setlength{\itemsep}{-.3ex}%
 
	}%
 
	{%
 
		\end{oldthebibliography}%
 
	}
 
@@ -749,102 +751,102 @@ The following lemma considers two vertices $v,w$ that are never ``crossed'' so t
 
	\end{align*}
 
	where there is no longer a condition on the starting state.
 
\end{lemma}
 
\begin{proof}
 
    We start by relating the different Markov Chains.
 
    If $b$ is a starting state where all the zeroes are inside an interval $[v,w]$ (not on the boundary) then we can switch between the cycle and the finite chain:
 
    \begin{align*}
 
        \P^{(n)}_{b} (\NZ{v,w} \cap A) = \P^{[v,w]}_b (\NZ{v,w}\cap A) .
 
    \end{align*}
 
    If vertex $v$ and $w$ never become zero, then the zeroes never get outside of the interval $[v,w]$ and we can ignore the entire circle and only focus on the process within $[v,w]$.
 
    We can apply this to the result of Lemma \ref{lemma:eventindependenceGen}, to get
 
    \begin{align*}
 
        \P^{(n)}_b(\mathrm{NZ}^{(v,w)} \cap A \cap B)
 
        &=
 
        \P^{[v,w]}_{b|_{[v,w]}}(\mathrm{NZ}^{(v,w)} \cap A)
 
        \; \cdot \;
 
        \P^{[w,v]}_{b|_{[w,v]}}(\mathrm{NZ}^{(v,w)} \cap B)
 
    \end{align*}
 
    Note that this also holds if $b$ has zeroes on the boundary (i.e. $b_v=0$ or $b_w=0$), because then both sides of the equations are zero.
 
    For the starting state we have the expression $\P^{(n)}(\start{b}) = (1-p)^{|b|} p^{n-|b|}$ so it splits into a product
 
    \begin{align*}
 
        \P^{(n)}(\start{b}) = \P^{[v,w]}(\start{b|_{[v+1,w-1]}}) \;\; \P^{[w,v]}(\start{b|_{[w,v]}})
 
    \end{align*}
 
    where we have to be careful to count the boudary only once.
 
    We now have
 
    \begin{align*}
 
		\P^{(n)}(\mathrm{NZ}^{(v,w)}\cap A\cap B)
 
        &= \sum_{b\in\{0,1\}^n} \P^{(n)}_b(\mathrm{NZ}^{(v,w)}\cap A\cap B) \; \P^{(n)}(\start{b}) \\
 
        &= \sum_{b\in\{0,1\}^n}
 
            \P^{[v,w]}_{b|_{[v,w]}}(\mathrm{NZ}^{(v,w)}\cap A)
 
            \P^{[v,w]}(\start{b|_{[v+1,w-1]}})
 
            \\ &\qquad\qquad\quad\cdot
 
            \P^{[w,v]}_{b|_{[w,v]}}(\mathrm{NZ}^{(v,w)}\cap B)
 
            \P^{[w,v]}(\start{b|_{[w,v]}}) \\
 
        &= \left( \sum_{\substack{b_1\in\{0,1\}^{[v,w]}\\ b_v=b_w=1}}
 
            \P^{[v,w]}_{b_1}(\mathrm{NZ}^{(v,w)}\cap A)
 
            \P^{[v,w]}(\start{b_1}) \right)
 
            \\ &\qquad \cdot
 
           \left( \sum_{b_2\in\{0,1\}^{[w,v]}}
 
            \P^{[w,v]}_{b_2}(\mathrm{NZ}^{(v,w)}\cap B)
 
            \P^{[w,v]}(\start{b_2}) \right) \\
 
        &=  \P^{[v,w]}_{b_v=b_w=1}(\mathrm{NZ}^{(v,w)}\cap A) \cdot
 
            \P^{[w,v]}(\mathrm{NZ}^{(v,w)}\cap B)
 
    \end{align*}
 
    The second equality follows in a similar way.
 
\end{proof}
 

	
 
	\begin{definition}[Connected patches]
 
		Let $P\subseteq V$ be a connected component of $G$. We say that $P$ is a patch of a particular run of the process if $P$ is a maximal connected component of the vertices that have ever become $0$ before termination. We denote the set of patches of a run by $\mathcal{P}$. For a patch $P$ let $P\in \mathcal{P}$ denote the event that one of the patches is equal to $P$. 
 
		Let $P\subseteq V$ be a connected component of $G$. We say that $P$ is a patch of a particular run of the process if $P$ is a maximal connected component of the vertices that have ever become $0$ before termination. We denote the set of patches of a run by $\mathcal{P}$. For a patch $P$ let $\patch{P}$ denote the event that one of the patches is equal to $P$. 
 
		In other words
 
		\begin{align*}
 
		P\in\mathcal{P} := \NZ{\overline{\partial}P} \cap \Z{P}.
 
		\patch{P} := \NZ{\overline{\partial}P} \cap \Z{P}.
 
		\end{align*}
 
		For $\mathcal{I}'\subseteq 2^{2^V}$ a set of patches we denote by $\mathcal{P}'\in \mathcal{P}$ the event that $\mathcal{P}'$ is a subset of the patches, i.e.,
 
		For a set of patches $\mathcal{P}$ 	</i>
 
		\begin{align*}
 
			\mathcal{P}'\in \mathcal{P} := \bigcup_{P\in \mathcal{P}'}\NZ{\overline{\partial}P} \cap \Z{P}.
 
		\end{align*}
 
	\end{definition} 
 

	
 
	We are often going to use the observation that we can partition the event $\Z{v}$ using patches:
 
	\begin{align*}
 
	\Z{v} = \dot\bigcup_{P\text{ patch } : v\in P} (P\in\mathcal{P})
 
	\end{align*}
 

	
 
The intuition of the following lemma is that the far right can only affect the zero vertex if there is an interaction chain forming, which means that every vertex should get resampled to $0$ at least once.
 
\begin{lemma}\label{lemma:probIndepNewGen}
 
	$\forall n\in \mathbb{N}_+:\P^{[n]}(\Z{1})-\P^{[n+1]}(\Z{1}) = \bigO{p^{n}}$. (Should be true with $\bigO{p^{n+1}}$ as well.)
 
\end{lemma}
 
\begin{proof}
 
	The proof uses induction on $n$. For $n=1$ the statement is easy, since $\P^{[1]}(\Z{1})=p$ and $\P^{[2]}(\Z{1})=p+p^2+\bigO{p^{3}}$.
 
	
 
	Induction step: suppose we proved the claim for $n-1$, then
 
	\begin{align*}
 
	\P^{[n+1]}(\Z{1})
 
	&=\sum_{k=1}^{n+1}\P^{[n+1]}([k]\in\mathcal{P}) \tag{the events form a partition}\\
 
	&=\sum_{k=1}^{n-1}\P^{[n+1]}([k]\in\mathcal{P}) + \bigO{p^{n}}\tag*{$\left(\P^{[n+1]}([k]\in\mathcal{P})=O(p^{k})\right)$}\\	
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}_{b_{k+1}=1}([k]\in\mathcal{P})\cdot \P^{[n-k+1]}(\NZ{1})+ \bigO{p^{n}} \tag{by Claim~\ref{lemma:eventindependenceNewGen}}\\
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}_{b_{k+1}=1}([k]\in\mathcal{P})\cdot \left(\P^{[n-k]}(\NZ{1})+\bigO{p^{n-k}}\right)+ \bigO{p^{n}} \tag{by induction} \\	
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}_{b_{k+1}=1}([k]\in\mathcal{P})\cdot \P^{[n-k]}(\NZ{1})+ \bigO{p^{n}} \tag*{$\left(\P^{[k+1]}_{b_{k+1}=1}([k]\in\mathcal{P})=\bigO{p^{k}}\right)$}\\	
 
	&=\sum_{k=1}^{n-1}\P^{[n]}([k]\in\mathcal{P})+ \bigO{p^{n}} \tag{by Claim~\ref{lemma:eventindependenceNewGen}}\\
 
	&=\sum_{k=1}^{n}\P^{[n]}([k]\in\mathcal{P})+ \bigO{p^{n}} \tag*{$\left(\P^{[n]}([n]\in\mathcal{P})=\bigO{p^{n}}\right)$}\\	
 
	&=\P^{[n]}(\Z{1})	+ \bigO{p^{n}} 
 
	\end{align*}
 
\end{proof}
 
\begin{corollary}\label{cor:probIndepNewGen}
 
	$\P^{[n]}(\Z{1})-\P^{[m]}(\Z{1}) = \bigO{p^{\min(n,m)}}$. (Should be true with $\bigO{p^{\min(n,m)+1}}$ too.)
 
\end{corollary}
 

	
 
	The intuition of the following lemma is simmilar to the previous. The events on the two sides should be independent unless an interaction chain is forming, implying that every vertex gets resampled to $0$ at least once.
 

	
 
 	\begin{lemma}\label{lemma:independenetSidesNewGen}	
 
 		$$\P^{[k]}(\Z{1}\cap \Z{k})=\P^{[k]}(\Z{1})\P^{[k]}(\Z{k})+\bigO{p^{k}}=\left(\P^{[k]}(\Z{1})\right)^2+\bigO{p^{k}}.$$
 
 	\end{lemma}   
 
 	Note that using De Morgan's law and the inclusion-exclusion formula we can see that this is equivalent to saying:
 
 	$$\P^{[k]}(\NZ{1}\cap \NZ{k})=\P^{[k]}(\NZ{1})\P^{[k]}(\NZ{k})+\bigO{p^{k}}.$$
 
 	\begin{proof}
 
 		We proceed by induction on $k$. For $k=1,2$ the statement is trivial.
 
 		
 
 		Now observe that:
 
 		$$\P^{[k]}(\Z{1})=\sum_{P\text{ patch}\,:\,1\in P}\P^{[k]}(P\in\mathcal{P})$$
 
 		$$\P^{[k]}(\Z{k})=\sum_{P\text{ patch}\,:\,k\in P}\P^{[k]}(P\in\mathcal{P})$$
 
 		
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