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Expand file tree Collapse file tree Original file line number Diff line number Diff line change 2222\begin {prop }\ollabel {prop:G2i-to-N2i}
2323If $ \Log {G2i} + \Cut \Proves \Gamma \Sequent \Delta $ then $ \Log {N2i}
2424\Proves \Gamma ' \Sequent !C$ , where $ !C \ident \lfalse $ if $ \Delta $ is
25- empty and $ \Delta = \{ !C \} $ otherwise, and $ \Gamma '$ corresponds
25+ empty and $ \Delta = \{ !A \} $ otherwise, and $ \Gamma '$ corresponds
2626to~$ \Gamma $ .
2727\end {prop }
2828
Original file line number Diff line number Diff line change 1414If $ \Log {N2ci} \Proves \Gamma \Sequent !A$ then $ \Log {G2ci} + \Cut \Proves
1515\Gamma ' \Sequent \Delta $ where $ \Gamma '$ is the multiset of
1616!!{formula}s resulting from $ \Gamma $ by removing labels, and $ \Delta =
17- \{ !C \} $ if $ !A$ is not~$ \lfalse $ , and $ \Delta = \emptyset $ if it is.
17+ \{ !A \} $ if $ !A$ is not~$ \lfalse $ , and $ \Delta = \emptyset $ if it is.
1818\end {prop }
1919
2020\begin {proof }
Original file line number Diff line number Diff line change 1212
1313If you have !!{prove}d a conditional~$ !A \lif !B$ , you might be in a
1414position to use it in !!a{proof} of~$ !B$ by using~\Elim {\lif }. This
15- would of course also a require !!a{proof}~$ \delta _1 $ of~$ !A$ . Your
15+ would of course also require !!a{proof}~$ \delta _1 $ of~$ !A$ . Your
1616!!{proof}~$ \delta _1 $ of~$ !A \lif !B$ , more likely than not, ends
1717in~\Intro {\lif }, which turns !!a{proof}~$ \delta _2 $ of~$ !B$ from the
1818open assumption~$ !A$ into one of~$ !A \lif !B$ . If it does, in your
Original file line number Diff line number Diff line change 1212
1313Cuts in \Log {N1i} are segments that end in the major premise of
1414!!a{elimination} rule. One case in the normalization proof is to
15- reduce the length of critical cuts, and with it the cut length of the
15+ reduce the length of maximal cuts, and with it the cut length of the
1616!!{proof}. A cut of length $ >1 $ can end in many ways depending on
1717whether the last !!{formula} occurrence of~$ !A$ in the cut is the
1818conclusion of (\Elim {\lor } or \Elim {\lexists }) and depending on the
Original file line number Diff line number Diff line change 101101rank }~$ \cutrank {\delta }$ of !!a{proof}~$ \delta $ is the maximal rank of
102102cuts in~$ \delta $ . A cut is \emph {maximal } in~$ \delta $ if its rank
103103is~$ \cutrank {\delta }$ , i.e., it has maximal rank. The \emph {cut length }
104- of~$ \delta $ is the sum of the lengths of all its critical cuts.
104+ of~$ \delta $ is the sum of the lengths of all its maximal cuts.
105105\end {defn }
106106
107107\end {document }
Original file line number Diff line number Diff line change 3333\end {cor }
3434
3535\begin {proof }
36- By inspection of the proof of \ollabel [nat][tgi]{prop:G2i-to-N2i}: we
36+ By inspection of the proof of \olref [nat][tgi]{prop:G2i-to-N2i}: we
3737add !!{introduction} rules to the end of !!{proof}s, and
3838!!{elimination} rules only at the top of !!{proof}s, so never
3939introduce an !!{introduction} rule above !!a{elimination} rule.
7373If $ \delta $ is a normal $ \Log {N2ci}$ -!!{proof} of~$ \Gamma \Sequent !A$
7474then there is a (cut-free) $ \Log {G2ci}$ -!!{proof}~$ \pi $ of $ \Gamma '
7575\Sequent \Delta $ , where $ \Gamma '$ is the multiset of !!{formula}s
76- resulting from $ \Gamma $ by removing labels, and $ \Delta = \{ !C \} $ if
76+ resulting from $ \Gamma $ by removing labels, and $ \Delta = \{ !A \} $ if
7777$ !A$ is not~$ \lfalse $ , and $ \Delta = \emptyset $ if it is.
7878\end {prop }
7979
Original file line number Diff line number Diff line change 4545the \emph {typed } $ \lambd $ -calculus. In the typed $ \lambd $ -calculus not
4646every expression $ (\lambd [x][N]M)$ is legal, but only those where the
4747`` types'' of $ \lambd [x][N]$ and $ M$ fit together, i.e., $ \lambd [x][N]$
48- has type $ A \lif B$ and $ M$ has type~$ A$ . In fact, not every term
49- $ (M_ 1 M_ 2 ) $ is legal only if $ x$ is of type $ A$ and $ N $ is of type only
50- those where $ M_ 1 $ has type $ A \to B $ and $ M_ 2 $ has type~ $ A $ ; if so,
51- then $ (M_1 M_2 )$ has type~ $ B $ . And if the type of $ x $ is $ A $ and the
52- type of $ N $ is $ B $ then the type of $ \lambd [x][N] $ is $ A \to B$ .
48+ has type $ A \lif B$ and $ M$ has type~$ A$ . The type of $ \lambd [x][N] $
49+ is $ A \to B $ only if the type of $ x$ is $ A$ and the type of $ N $
50+ is~ $ B $ . In general, not every expression $ (M_ 1 M_ 2 ) $ is legal. Only
51+ those terms $ (M_1 M_2 )$ are legal where $ M_ 1 $ has type $ A \to B $ and
52+ $ M_ 2 $ has type~ $ A $ ; if so, then $ (M_ 1 M_ 2 ) $ has type~ $ B$ .
5353
5454These typing rules now clearly correspond to !!{derivation}s in
5555natural deduction, where the types are represented by !!{formula}s,
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