Changeset - 29be8ea7ee3c
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András Gilyén - 8 years ago 2017-09-07 02:44:49
gilyen@cwi.nl
simplified proof
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@@ -645,49 +645,49 @@ The intuition of the following lemma is that the far right can only affect the z
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}([k]\in\mathcal{P})\cdot \P^{[n-k+1]}(\NZ{1})/(1-p)+ O(p^{n}) \tag{by Claim~\ref{lemma:eventindependenceNew}}\\
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}([k]\in\mathcal{P})\cdot \left(\P^{[n-k]}(\NZ{1})+O(p^{n-k})\right)/(1-p)+ O(p^{n}) \tag{by induction} \\	
 
	&=\sum_{k=1}^{n-1}\P^{[k+1]}([k]\in\mathcal{P})\cdot \P^{[n-k]}(\NZ{1})/(1-p)+ O(p^{n}) \\	
 
	&=\sum_{k=1}^{n-1}\P^{[n]}([k]\in\mathcal{P})+ O(p^{n}) \tag{by Claim~\ref{lemma:eventindependenceNew}}\\
 
	&=\sum_{k=1}^{n}\P^{[n]}([k]\in\mathcal{P})+ O(p^{n}) \\
 
	&=\P^{[n]}(\Z{1})	+ O(p^{n}) 
 
	\end{align*}
 
\end{proof}
 
\begin{corollary}\label{cor:probIndepNew}
 
	$\P^{[n]}(\Z{1})-\P^{[m]}(\Z{1}) = O(p^{\min(n,m)})$. (Should be true with $O(p^{\min(n,m)+1})$ too.)
 
\end{corollary}
 

	
 
 	\begin{lemma}\label{lemma:independenetSidesNew}	
 
 		$$\P^{[k]}(\Z{1}\cap \Z{k})=\P^{[k]}(\Z{1})\P^{[k]}(\Z{k})+\mathcal{O}(p^{k})=\left(\P^{[k]}(\Z{1})\right)^2+\mathcal{O}(p^{k}).$$
 
 	\end{lemma}   
 
 	Note that using De Morgan's law and the inclusion-exclusion formula we can see that this is equivalent to saying:
 
 	$$\P^{[k]}(\NZ{1}\cap \NZ{k})=\P^{[k]}(\NZ{1})\P^{[k]}(\NZ{k})+\mathcal{O}(p^{k}).$$
 
 	\begin{proof}
 
 		We proceed by induction on $k$. For $k=1,2$ the statement is trivial.
 
 		
 
 		Now observe that:
 
 		$$\P^{[k]}(\Z{1})=\sum_{P\text{ patch}\,:\,1\in P}\P^{[k]}(P\in\mathcal{P})$$
 
 		$$\P^{[k]}(\Z{k})=\sum_{P\text{ patch}\,:\,k\in P}\P^{[k]}(P\in\mathcal{P})$$
 
 		
 
 		Suppose we proved the statement up to $k-$, then we proceed using induction similarly to the above
 
 		Suppose we proved the statement up to $k-1$, then we proceed using induction similarly to the above
 
 		\begin{align*}
 
 		&\P^{[k]}(\Z{1}\cap \Z{k})=\\
 
 		&=\sum_{\ell, r\in [k]: \ell<r-1}\P^{[k]}([\ell],[r,k]\in\mathcal{P})
 
 		+\P^{[k]}([k]\in\mathcal{P})\\
 
 		&=\sum_{\ell, r\in [k]: \ell<r-1}\P^{[k]}([\ell],[r,k]\in\mathcal{P})
 
 		+\mathcal{O}(p^{k})\\
 
 		&\overset{Lemma~\ref{lemma:eventindependenceNew}}{=}\sum_{\ell, r\in [k]: \ell<r-1}
 
 		\P^{[\ell+1]}([\ell]\in\mathcal{P})
 
 		\P^{[\ell+1,r-1]}(\NZ{\ell+1}\cap \NZ{r-1})
 
 		\P^{[r-1,k]}([r,k]\in\mathcal{P})/(1-p)^2
 
 		+\mathcal{O}(p^{k})\\
 
 		&\overset{\text{induction}}{=}\sum_{\ell, r\in [k]: \ell<r-1}
 
 		\P^{[\ell+1]}([\ell]\in\mathcal{P})
 
 		\left(\P^{[\ell+1,r-1]}(\NZ{\ell+1})
 
		\P^{[\ell+1,r-1]}(\NZ{r-1})\right)
 
 		\P^{[r-1,k]}([r,k]\in\mathcal{P})/(1-p)^2
 
 		+\mathcal{O}(p^{k})\\
 
 		&\overset{Corrolary~\ref{cor:probIndepNew}}{=}\sum_{\ell, r\in [k]: \ell<r-1}
 
 		\P^{[\ell+1]}([\ell]\in\mathcal{P})
 
 		\left(\P^{[\ell+1,k]}(\NZ{\ell+1})
 
 		\P^{[1,r-1]}(\NZ{r-1})\right)
 
 		\P^{[r-1,k]}([r,k]\in\mathcal{P})/(1-p)^2
 
 		+\mathcal{O}(p^{k})\\
 
 		&\overset{Lemma~\ref{lemma:eventindependenceNew}}{=}\sum_{\ell, r\in [k]: \ell<r-1}
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