Révision 228

CSL17/arithmetic.tex (revision 228)
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\begin{figure}
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	\[
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	\small
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	\hspace{-1.5em}
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	\begin{array}{l}
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	\begin{array}{cccc}
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	%\vlinf{\lefrul{\bot}}{}{p, \lnot{p} \seqar }{}
......
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	%& \vlinf{\rigrul{\bot}}{}{\seqar p, \lnot{p}}{}
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	%& \vliinf{\cut}{}{\Gamma, \Sigma \seqar \Delta , \Pi}{ \Gamma \seqar \Delta, A }{\Sigma, A \seqar \Pi}
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	\vlinf{id}{}{\Gamma, p \seqar p, \Delta }{}
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	& \vliinf{cut}{}{\Gamma \seqar \Delta }{ \Gamma \seqar \Delta, A }{\Gamma, A \seqar \Delta}
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	&&
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	& \vliinf{cut}{}{\Gamma, \Sigma \seqar \Delta, \Pi }{ \Gamma \seqar \Delta, A }{\Sigma, A \seqar \Pi}
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	&	\vlinf{\lefrul{\neg}}{}{\Gamma, \neg A \seqar \Delta}{\Gamma \seqar A, \Delta}
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	&
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	\vlinf{\rigrul{\neg}}{}{\Gamma, \seqar \neg A, \Delta}{\Gamma, A \seqar  \Delta}
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		\\
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		\noalign{\bigskip}
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		%\text{Structural:} & & & \\
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		%\noalign{\bigskip}
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		\vlinf{\lefrul{\wk}}{}{\Gamma, A \seqar \Delta}{\Gamma \seqar \Delta}
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		&
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		\vlinf{\lefrul{\cntr}}{}{\Gamma, A \seqar \Delta}{\Gamma, A, A \seqar \Delta}
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		&
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		\vlinf{\rigrul{\wk}}{}{\Gamma \seqar \Delta, A }{\Gamma \seqar \Delta}
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		&
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		\vlinf{\rigrul{\cntr}}{}{\Gamma \seqar \Delta, A}{\Gamma \seqar \Delta, A, A}
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		\\
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		\noalign{\bigskip}
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		\vlinf{\lefrul{\exists}}{}{\Gamma, \exists x . A(x) \seqar \Delta}{\Gamma, A(a) \seqar \Delta}
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		&
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		\vlinf{\lefrul{\forall}}{}{\Gamma, \forall x. A(x) \seqar \Delta}{\Gamma, A(t) \seqar \Delta}
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		&
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		\vlinf{\rigrul{\exists}}{}{\Gamma \seqar \Delta, \exists x . A(x)}{ \Gamma \seqar \Delta, A(t)}
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		&
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		\vlinf{\rigrul{\forall}}{}{\Gamma \seqar \Delta, \forall x . A(x)}{ \Gamma \seqar \Delta, A(a) }
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	\\
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	\noalign{\bigskip}
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	%\noalign{\bigskip}
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	\vliinf{\lefrul{\cor}}{}{\Gamma, A \cor B \seqar \Delta}{\Gamma , A \seqar \Delta}{\Gamma, B \seqar \Delta}
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	\vliinf{\lefrul{\cor}}{}{\Gamma, \Sigma, A \cor B \seqar \Delta, \Pi}{\Gamma , A \seqar \Delta}{\Sigma, B \seqar \Pi}
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	&
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	\vlinf{\lefrul{\cand}}{}{\Gamma, A\cand B \seqar \Delta}{\Gamma, A , B \seqar \Delta}
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	&
......
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	&
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	%\vlinf{\rigrul{\laor}}{}{\Gamma \seqar \Delta, A\laor B}{\Gamma \seqar \Delta, B}
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	%\quad
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	\vliinf{\rigrul{\cand}}{}{\Gamma \seqar \Delta, A \cand B }{\Gamma \seqar \Delta, A}{\Gamma \seqar \Delta, B}
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	\\
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	\noalign{\bigskip}
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	\vlinf{\lefrul{\neg}}{}{\Gamma, \neg A \seqar \Delta}{\Gamma \seqar A, \Delta}
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	&
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	\vlinf{\lefrul{\neg}}{}{\Gamma, \seqar \neg A, \Delta}{\Gamma, A \seqar  \Delta}
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	&
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	&
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	%\vliinf{\lefrul{\cimp}}{}{\Gamma, A \cimp B \seqar \Delta}{\Gamma \seqar A, \Delta}{\Gamma, B \seqar \Delta}
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	%&
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	%
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	%\vlinf{\rigrul{\cimp}}{}{\Gamma \seqar \Delta, A \cimp B}{\Gamma, A \seqar \Delta,  B}
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	\\
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	\noalign{\bigskip}
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	%\text{Structural:} & & & \\
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	\vliinf{\rigrul{\cand}}{}{\Gamma, \Sigma \seqar \Delta, \Pi, A \cand B }{\Gamma \seqar \Delta, A}{\Sigma \seqar \Pi, B}
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	%\noalign{\bigskip}
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	%\vlinf{\lefrul{\wk}}{}{\Gamma, A \seqar \Delta}{\Gamma \seqar \Delta}
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	%&
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	\vlinf{\lefrul{\cntr}}{}{\Gamma, A \seqar \Delta}{\Gamma, A, A \seqar \Delta}
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	%&
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	%\vlinf{\rigrul{\wk}}{}{\Gamma \seqar \Delta, A }{\Gamma \seqar \Delta}
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	&
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	\vlinf{\rigrul{\cntr}}{}{\Gamma \seqar \Delta, A}{\Gamma \seqar \Delta, A, A}
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	&
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	&
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	\\
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	\noalign{\bigskip}
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	\vlinf{\lefrul{\exists}}{}{\Gamma, \exists x . A(x) \seqar \Delta}{\Gamma, A(a) \seqar \Delta}
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	&
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	\vlinf{\lefrul{\forall}}{}{\Gamma, \forall x. A(x) \seqar \Delta}{\Gamma, A(t) \seqar \Delta}
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	&
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	\vlinf{\rigrul{\exists}}{}{\Gamma \seqar \Delta, \exists x . A(x)}{ \Gamma \seqar \Delta, A(t)}
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	&
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	\vlinf{\rigrul{\forall}}{}{\Gamma \seqar \Delta, \forall x . A(x)}{ \Gamma \seqar \Delta, A(a) } \\
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	%\noalign{\bigskip}
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	% \vliinf{mix}{}{\Gamma, \Sigma \seqar \Delta , \Pi}{ \Gamma \seqar \Delta}{\Sigma \seqar \Pi} &&&
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	\end{array}
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	\end{array}
......
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\end{theorem}
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Strictly speaking, we must alter some of the sequent rules a little to arrive at this normal form. For instance the $\pind$ rule would have $\normal(\vec u)$ in its lower sequent rather than $\normal (t(\vec u))$. The latter is a consequence of the former already in $\basic$.
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The proof of this result also relies on a heavy use of the structural rules, contraction and weakening, to ensure that we always have a complete and compatible typing on the LHS of a sequent. This is similar to what is done in \cite{OstrinWainer05} where they use a $G3$ style calculus to manage such structural manipulations.
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The proof of this result also relies on a heavy use of the structural rules, contraction and weakening, to ensure that we always have a complete and compatible sorting of variables on the LHS of a sequent. This is similar to what is done in \cite{OstrinWainer05} where they use a $G3$ style calculus to manage such structural manipulations.
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As we mentioned, the fact that only $\Sigma^\safe_i$ formulae occur is due to the free-cut elimination result for first-order calculi \cite{Takeuti87,Cook:2010:LFP:1734064}, which gives a form of proof where every $\cut$ step has one of its cut formulae immediately below a non-logical step. Again, we have to adapt the $\rais$ rule a little to achieve our result, due to the fact that it has a $\exists x^\normal$ in its lower sequent. For this we consider a merge of $\rais$ and $\cut$, which allows us to directly cut the upper sequent of $\rais$ against a sequent of the form $\normal(u), A(u), \Gamma \seqar \Delta$.
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Finally, as is usual in bounded arithmetic, we use distinguished rules for our relativised quantifiers, e.g.\
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\todo{}

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