removal of FOL and ZF
Wed Jan 13 16:30:53 1999 +0100 (1999-01-13)
changeset 6120f40d61cd6b32
parent 6119 7e3eb9b4df8e
child 6121 5fe77b9b5185
removal of FOL and ZF
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/doc-src/Logics/preface.tex	Wed Jan 13 16:30:53 1999 +0100
     1.3 @@ -0,0 +1,60 @@
     1.4 +%% $Id$
     1.5 +\chapter*{Preface}
     1.6 +Several logics come with Isabelle.  Many of them are sufficiently developed
     1.7 +to serve as comfortable reasoning environments.  They are also good
     1.8 +starting points for defining new logics.  Each logic is distributed with
     1.9 +sample proofs, some of which are described in this document.
    1.10 +
    1.11 +The logics \texttt{FOL} (first-order logic) and \texttt{ZF} (axiomatic set
    1.12 +theory) are described in a separate manual~\cite{isabelle-ZF}.  Here are the
    1.13 +others:
    1.14 +
    1.15 +\begin{ttdescription}
    1.16 +\item[\thydx{CCL}] is Martin Coen's Classical Computational Logic,
    1.17 +  which is the basis of a preliminary method for deriving programs from
    1.18 +  proofs~\cite{coen92}.  It is built upon classical~\FOL{}.
    1.19 + 
    1.20 +\item[\thydx{LCF}] is a version of Scott's Logic for Computable
    1.21 +  Functions, which is also implemented by the~{\sc lcf}
    1.22 +  system~\cite{paulson87}.  It is built upon classical~\FOL{}.
    1.23 +
    1.24 +\item[\thydx{HOL}] is the higher-order logic of Church~\cite{church40},
    1.25 +which is also implemented by Gordon's~{\sc hol} system~\cite{mgordon-hol}.
    1.26 +This object-logic should not be confused with Isabelle's meta-logic, which is
    1.27 +also a form of higher-order logic.
    1.28 +
    1.29 +\item[\thydx{HOLCF}] is a version of {\sc lcf}, defined as an
    1.30 +  extension of \texttt{HOL}\@.
    1.31 + 
    1.32 +\item[\thydx{CTT}] is a version of Martin-L\"of's Constructive Type
    1.33 +Theory~\cite{nordstrom90}, with extensional equality.  Universes are not
    1.34 +included.
    1.35 +
    1.36 +\item[\thydx{Cube}] is Barendregt's $\lambda$-cube.
    1.37 + \end{ttdescription}
    1.38 +
    1.39 +The directory \texttt{Sequents} contains several logics based
    1.40 +  upon the sequent calculus.  Sequents have the form $A@1,\ldots,A@m\turn
    1.41 +B@1,\ldots,B@n$; rules are applied using associative matching.
    1.42 +\begin{ttdescription}
    1.43 +\item[\thydx{LK}] is classical first-order logic as a sequent calculus.
    1.44 +
    1.45 +\item[\thydx{Modal}] implements the modal logics $T$, $S4$, and~$S43$.  
    1.46 +
    1.47 +\item[\thydx{ILL}] implements intuitionistic linear logic.
    1.48 +\end{ttdescription}
    1.49 +
    1.50 +The logics \texttt{CCL}, \texttt{LCF}, \texttt{HOLCF}, \texttt{Modal}, \texttt{ILL} and {\tt
    1.51 +  Cube} are undocumented.  All object-logics' sources are
    1.52 +distributed with Isabelle (see the directory \texttt{src}).  They are
    1.53 +also available for browsing on the WWW at
    1.54 +\begin{ttbox}
    1.55 +
    1.56 +\end{ttbox}
    1.57 +Note that this is not necessarily consistent with your local sources!
    1.58 +
    1.59 +\medskip Do not read this manual before reading \emph{Introduction to
    1.60 +  Isabelle} and performing some Isabelle proofs.  Consult the {\em Reference
    1.61 +  Manual} for more information on tactics, packages, etc.
    1.62 +
    1.63 +
     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/doc-src/Logics/syntax.tex	Wed Jan 13 16:30:53 1999 +0100
     2.3 @@ -0,0 +1,62 @@
     2.4 +%% $Id$
     2.6 +
     2.7 +\chapter{Syntax definitions}
     2.8 +The syntax of each logic is presented using a context-free grammar.
     2.9 +These grammars obey the following conventions:
    2.10 +\begin{itemize}
    2.11 +\item identifiers denote nonterminal symbols
    2.12 +\item \texttt{typewriter} font denotes terminal symbols
    2.13 +\item parentheses $(\ldots)$ express grouping
    2.14 +\item constructs followed by a Kleene star, such as $id^*$ and $(\ldots)^*$
    2.15 +can be repeated~0 or more times 
    2.16 +\item alternatives are separated by a vertical bar,~$|$
    2.17 +\item the symbol for alphanumeric identifiers is~{\it id\/} 
    2.18 +\item the symbol for scheme variables is~{\it var}
    2.19 +\end{itemize}
    2.20 +To reduce the number of nonterminals and grammar rules required, Isabelle's
    2.21 +syntax module employs {\bf priorities},\index{priorities} or precedences.
    2.22 +Each grammar rule is given by a mixfix declaration, which has a priority,
    2.23 +and each argument place has a priority.  This general approach handles
    2.24 +infix operators that associate either to the left or to the right, as well
    2.25 +as prefix and binding operators.
    2.26 +
    2.27 +In a syntactically valid expression, an operator's arguments never involve
    2.28 +an operator of lower priority unless brackets are used.  Consider
    2.29 +first-order logic, where $\exists$ has lower priority than $\disj$,
    2.30 +which has lower priority than $\conj$.  There, $P\conj Q \disj R$
    2.31 +abbreviates $(P\conj Q) \disj R$ rather than $P\conj (Q\disj R)$.  Also,
    2.32 +$\exists x.P\disj Q$ abbreviates $\exists x.(P\disj Q)$ rather than
    2.33 +$(\exists x.P)\disj Q$.  Note especially that $P\disj(\exists x.Q)$
    2.34 +becomes syntactically invalid if the brackets are removed.
    2.35 +
    2.36 +A {\bf binder} is a symbol associated with a constant of type
    2.37 +$(\sigma\To\tau)\To\tau'$.  For instance, we may declare~$\forall$ as
    2.38 +a binder for the constant~$All$, which has type $(\alpha\To o)\To o$.
    2.39 +This defines the syntax $\forall x.t$ to mean $All(\lambda x.t)$.  We
    2.40 +can also write $\forall x@1\ldots x@m.t$ to abbreviate $\forall x@1.
    2.41 +\ldots \forall x@m.t$; this is possible for any constant provided that
    2.42 +$\tau$ and $\tau'$ are the same type.  \HOL's description operator
    2.43 +$\varepsilon x.P\,x$ has type $(\alpha\To bool)\To\alpha$ and can bind
    2.44 +only one variable, except when $\alpha$ is $bool$.  \ZF's bounded
    2.45 +quantifier $\forall x\in A.P(x)$ cannot be declared as a binder
    2.46 +because it has type $[i, i\To o]\To o$.  The syntax for binders allows
    2.47 +type constraints on bound variables, as in
    2.48 +\[ \forall (x{::}\alpha) \; (y{::}\beta) \; z{::}\gamma. Q(x,y,z) \]
    2.49 +
    2.50 +To avoid excess detail, the logic descriptions adopt a semi-formal style.
    2.51 +Infix operators and binding operators are listed in separate tables, which
    2.52 +include their priorities.  Grammar descriptions do not include numeric
    2.53 +priorities; instead, the rules appear in order of decreasing priority.
    2.54 +This should suffice for most purposes; for full details, please consult the
    2.55 +actual syntax definitions in the {\tt.thy} files.
    2.56 +
    2.57 +Each nonterminal symbol is associated with some Isabelle type.  For
    2.58 +example, the formulae of first-order logic have type~$o$.  Every
    2.59 +Isabelle expression of type~$o$ is therefore a formula.  These include
    2.60 +atomic formulae such as $P$, where $P$ is a variable of type~$o$, and more
    2.61 +generally expressions such as $P(t,u)$, where $P$, $t$ and~$u$ have
    2.62 +suitable types.  Therefore, `expression of type~$o$' is listed as a
    2.63 +separate possibility in the grammar for formulae.
    2.64 +
    2.65 +