--- a/doc-src/IsarRef/Thy/Introduction.thy Thu May 26 22:42:52 2011 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,73 +0,0 @@
-theory Introduction
-imports Base Main
-begin
-
-chapter {* Introduction *}
-
-section {* Overview *}
-
-text {*
- The \emph{Isabelle} system essentially provides a generic
- infrastructure for building deductive systems (programmed in
- Standard ML), with a special focus on interactive theorem proving in
- higher-order logics. Many years ago, even end-users would refer to
- certain ML functions (goal commands, tactics, tacticals etc.) to
- pursue their everyday theorem proving tasks.
-
- In contrast \emph{Isar} provides an interpreted language environment
- of its own, which has been specifically tailored for the needs of
- theory and proof development. Compared to raw ML, the Isabelle/Isar
- top-level provides a more robust and comfortable development
- platform, with proper support for theory development graphs, managed
- transactions with unlimited undo etc. The Isabelle/Isar version of
- the \emph{Proof~General} user interface
- \cite{proofgeneral,Aspinall:TACAS:2000} provides a decent front-end
- for interactive theory and proof development in this advanced
- theorem proving environment, even though it is somewhat biased
- towards old-style proof scripts.
-
- \medskip Apart from the technical advances over bare-bones ML
- programming, the main purpose of the Isar language is to provide a
- conceptually different view on machine-checked proofs
- \cite{Wenzel:1999:TPHOL,Wenzel-PhD}. \emph{Isar} stands for
- \emph{Intelligible semi-automated reasoning}. Drawing from both the
- traditions of informal mathematical proof texts and high-level
- programming languages, Isar offers a versatile environment for
- structured formal proof documents. Thus properly written Isar
- proofs become accessible to a broader audience than unstructured
- tactic scripts (which typically only provide operational information
- for the machine). Writing human-readable proof texts certainly
- requires some additional efforts by the writer to achieve a good
- presentation, both of formal and informal parts of the text. On the
- other hand, human-readable formal texts gain some value in their own
- right, independently of the mechanic proof-checking process.
-
- Despite its grand design of structured proof texts, Isar is able to
- assimilate the old tactical style as an ``improper'' sub-language.
- This provides an easy upgrade path for existing tactic scripts, as
- well as some means for interactive experimentation and debugging of
- structured proofs. Isabelle/Isar supports a broad range of proof
- styles, both readable and unreadable ones.
-
- \medskip The generic Isabelle/Isar framework (see
- \chref{ch:isar-framework}) works reasonably well for any Isabelle
- object-logic that conforms to the natural deduction view of the
- Isabelle/Pure framework. Specific language elements introduced by
- the major object-logics are described in \chref{ch:hol}
- (Isabelle/HOL), \chref{ch:holcf} (Isabelle/HOLCF), and \chref{ch:zf}
- (Isabelle/ZF). The main language elements are already provided by
- the Isabelle/Pure framework. Nevertheless, examples given in the
- generic parts will usually refer to Isabelle/HOL as well.
-
- \medskip Isar commands may be either \emph{proper} document
- constructors, or \emph{improper commands}. Some proof methods and
- attributes introduced later are classified as improper as well.
- Improper Isar language elements, which are marked by ``@{text
- "\<^sup>*"}'' in the subsequent chapters; they are often helpful
- when developing proof documents, but their use is discouraged for
- the final human-readable outcome. Typical examples are diagnostic
- commands that print terms or theorems according to the current
- context; other commands emulate old-style tactical theorem proving.
-*}
-
-end