--- a/CookBook/Package/Ind_General_Scheme.thy Wed Mar 18 23:52:51 2009 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,87 +0,0 @@
-theory Ind_General_Scheme
-imports Main
-begin
-
-section{* The General Construction Principle \label{sec:ind-general-method} *}
-
-text {*
-
- The point of these examples is to get a feeling what the automatic proofs
- should do in order to solve all inductive definitions we throw at them. For this
- it is instructive to look at the general construction principle
- of inductive definitions, which we shall do in the next section.
-
- Before we start with the implementation, it is useful to describe the general
- form of inductive definitions that our package should accept.
- Suppose $R_1,\ldots,R_n$ be mutually inductive predicates and $\vec{p}$ be
- some fixed parameters. Then the introduction rules for $R_1,\ldots,R_n$ may have
- the form
-
- \[
- \bigwedge\vec{x}_i.~\vec{A}_i \Longrightarrow \left(\bigwedge\vec{y}_{ij}.~\vec{B}_{ij} \Longrightarrow
- R_{k_{ij}}~\vec{p}~\vec{s}_{ij}\right)_{j=1,\ldots,m_i} \Longrightarrow R_{l_i}~\vec{p}~\vec{t}_i
- \qquad \mbox{for\ } i=1,\ldots,r
- \]
-
- where $\vec{A}_i$ and $\vec{B}_{ij}$ are formulae not containing $R_1,\ldots,R_n$.
- Note that by disallowing the inductive predicates to occur in $\vec{B}_{ij}$ we make sure
- that all occurrences of the predicates in the premises of the introduction rules are
- \emph{strictly positive}. This condition guarantees the existence of predicates
- that are closed under the introduction rules shown above. Then the definitions of the
- inductive predicates $R_1,\ldots,R_n$ is:
-
- \[
- \begin{array}{l@ {\qquad}l}
- R_i \equiv \lambda\vec{p}~\vec{z}_i.~\forall P_1 \ldots P_n.~K_1 \longrightarrow \cdots \longrightarrow K_r \longrightarrow P_i~\vec{z}_i &
- \mbox{for\ } i=1,\ldots,n \\[1.5ex]
- \mbox{where} \\
- K_i \equiv \forall\vec{x}_i.~\vec{A}_i \longrightarrow \left(\forall\vec{y}_{ij}.~\vec{B}_{ij} \longrightarrow
- P_{k_{ij}}~\vec{s}_{ij}\right)_{j=1,\ldots,m_i} \longrightarrow P_{l_i}~\vec{t}_i &
- \mbox{for\ } i=1,\ldots,r
- \end{array}
- \]
-
- The induction principles for the inductive predicates $R_1,\ldots,R_n$ are
-
- \[
- \begin{array}{l@ {\qquad}l}
- R_i~\vec{p}~\vec{z}_i \Longrightarrow I_1 \Longrightarrow \cdots \Longrightarrow I_r \Longrightarrow P_i~\vec{z}_i &
- \mbox{for\ } i=1,\ldots,n \\[1.5ex]
- \mbox{where} \\
- I_i \equiv \bigwedge\vec{x}_i.~\vec{A}_i \Longrightarrow \left(\bigwedge\vec{y}_{ij}.~\vec{B}_{ij} \Longrightarrow
- P_{k_{ij}}~\vec{s}_{ij}\right)_{j=1,\ldots,m_i} \Longrightarrow P_{l_i}~\vec{t}_i &
- \mbox{for\ } i=1,\ldots,r
- \end{array}
- \]
-
- Since $K_i$ and $I_i$ are equivalent modulo conversion between meta-level and object-level
- connectives, it is clear that the proof of the induction theorem is straightforward. We will
- therefore focus on the proof of the introduction rules. When proving the introduction rule
- shown above, we start by unfolding the definition of $R_1,\ldots,R_n$, which yields
-
- \[
- \bigwedge\vec{x}_i.~\vec{A}_i \Longrightarrow \left(\bigwedge\vec{y}_{ij}.~\vec{B}_{ij} \Longrightarrow
- \forall P_1 \ldots P_n.~\vec{K} \longrightarrow P_{k_{ij}}~\vec{s}_{ij}\right)_{j=1,\ldots,m_i} \Longrightarrow \forall P_1 \ldots P_n.~\vec{K} \longrightarrow P_{l_i}~\vec{t}_i
- \]
-
- where $\vec{K}$ abbreviates $K_1,\ldots,K_r$. Applying the introduction rules for
- $\forall$ and $\longrightarrow$ yields a goal state in which we have to prove $P_{l_i}~\vec{t}_i$
- from the additional assumptions $\vec{K}$. When using $K_{l_i}$ (converted to the meta-logic format)
- to prove $P_{l_i}~\vec{t}_i$, we get subgoals $\vec{A}_i$ that are trivially solvable by assumption,
- as well as subgoals of the form
-
- \[
- \bigwedge\vec{y}_{ij}.~\vec{B}_{ij} \Longrightarrow P_{k_{ij}}~\vec{s}_{ij} \qquad \mbox{for\ } j=1,\ldots,m_i
- \]
-
- that can be solved using the assumptions
-
- \[
- \bigwedge\vec{y}_{ij}.~\vec{B}_{ij} \Longrightarrow
- \forall P_1 \ldots P_n.~\vec{K} \longrightarrow P_{k_{ij}}~\vec{s}_{ij} \qquad \mbox{and} \qquad \vec{K}
- \]
-
- What remains is to implement these proofs generically.
-*}
-
-end