author | wenzelm |
Sat, 05 Apr 2014 15:03:40 +0200 | |
changeset 56421 | 1ffd7eaa778b |
parent 51058 | 98c48d023136 |
permissions | -rw-r--r-- |
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theory Preface |
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imports Base Main |
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begin |
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chapter {* Preface *} |
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text {* |
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The \emph{Isabelle} system essentially provides a generic |
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infrastructure for building deductive systems (programmed in |
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Standard ML), with a special focus on interactive theorem proving in |
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higher-order logics. Many years ago, even end-users would refer to |
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certain ML functions (goal commands, tactics, tacticals etc.) to |
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pursue their everyday theorem proving tasks. |
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In contrast \emph{Isar} provides an interpreted language environment |
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of its own, which has been specifically tailored for the needs of |
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theory and proof development. Compared to raw ML, the Isabelle/Isar |
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top-level provides a more robust and comfortable development |
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platform, with proper support for theory development graphs, managed |
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transactions with unlimited undo etc. |
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In its pioneering times, the Isabelle/Isar version of the |
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\emph{Proof~General} user interface |
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\cite{proofgeneral,Aspinall:TACAS:2000} has contributed to the |
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success of for interactive theory and proof development in this |
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advanced theorem proving environment, even though it was somewhat |
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biased towards old-style proof scripts. The more recent |
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Isabelle/jEdit Prover IDE \cite{Wenzel:2012} emphasizes the |
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document-oriented approach of Isabelle/Isar again more explicitly. |
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\medskip Apart from the technical advances over bare-bones ML |
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programming, the main purpose of the Isar language is to provide a |
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conceptually different view on machine-checked proofs |
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\cite{Wenzel:1999:TPHOL,Wenzel-PhD}. \emph{Isar} stands for |
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\emph{Intelligible semi-automated reasoning}. Drawing from both the |
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traditions of informal mathematical proof texts and high-level |
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programming languages, Isar offers a versatile environment for |
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structured formal proof documents. Thus properly written Isar |
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proofs become accessible to a broader audience than unstructured |
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tactic scripts (which typically only provide operational information |
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for the machine). Writing human-readable proof texts certainly |
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requires some additional efforts by the writer to achieve a good |
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presentation, both of formal and informal parts of the text. On the |
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other hand, human-readable formal texts gain some value in their own |
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right, independently of the mechanic proof-checking process. |
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Despite its grand design of structured proof texts, Isar is able to |
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assimilate the old tactical style as an ``improper'' sub-language. |
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This provides an easy upgrade path for existing tactic scripts, as |
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well as some means for interactive experimentation and debugging of |
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structured proofs. Isabelle/Isar supports a broad range of proof |
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styles, both readable and unreadable ones. |
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\medskip The generic Isabelle/Isar framework (see |
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\chref{ch:isar-framework}) works reasonably well for any Isabelle |
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object-logic that conforms to the natural deduction view of the |
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Isabelle/Pure framework. Specific language elements introduced by |
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Isabelle/HOL are described in \partref{part:hol}. Although the main |
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language elements are already provided by the Isabelle/Pure |
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framework, examples given in the generic parts will usually refer to |
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removed outdated IsarRef/Thy/HOLCF_Specific.thy -- make IsarRef depend on HOL only;
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parents:
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Isabelle/HOL. |
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\medskip Isar commands may be either \emph{proper} document |
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constructors, or \emph{improper commands}. Some proof methods and |
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attributes introduced later are classified as improper as well. |
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Improper Isar language elements, which are marked by ``@{text |
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"\<^sup>*"}'' in the subsequent chapters; they are often helpful |
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when developing proof documents, but their use is discouraged for |
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the final human-readable outcome. Typical examples are diagnostic |
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commands that print terms or theorems according to the current |
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context; other commands emulate old-style tactical theorem proving. |
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*} |
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end |