
diff -r 0e2a29a1065c -r cc127cc0951b doc-src/IsarRef/Thy/pure.thy
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc-src/IsarRef/Thy/pure.thy	Fri May 02 16:36:05 2008 +0200
@@ -0,0 +1,1792 @@
+(* $Id$ *)
+
+theory pure
+imports CPure
+begin
+
+chapter {* Basic language elements \label{ch:pure-syntax} *}
+
+text {*
+  Subsequently, we introduce the main part of Pure theory and proof
+  commands, together with fundamental proof methods and attributes.
+  \Chref{ch:gen-tools} describes further Isar elements provided by
+  generic tools and packages (such as the Simplifier) that are either
+  part of Pure Isabelle or pre-installed in most object logics.
+  \Chref{ch:logics} refers to object-logic specific elements (mainly
+  for HOL and ZF).
+
+  \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 subsequently marked by
+  ``@{text "\<^sup>*"}'', are often helpful when developing proof
+  documents, while 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.
+*}
+
+
+section {* Theory commands *}
+
+subsection {* Defining theories \label{sec:begin-thy} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "header"} & : & \isarkeep{toplevel} \\
+    @{command_def "theory"} & : & \isartrans{toplevel}{theory} \\
+    @{command_def "end"} & : & \isartrans{theory}{toplevel} \\
+  \end{matharray}
+
+  Isabelle/Isar theories are defined via theory, which contain both
+  specifications and proofs; occasionally definitional mechanisms also
+  require some explicit proof.
+
+  The first ``real'' command of any theory has to be @{command
+  "theory"}, which starts a new theory based on the merge of existing
+  ones.  Just preceding the @{command "theory"} keyword, there may be
+  an optional @{command "header"} declaration, which is relevant to
+  document preparation only; it acts very much like a special
+  pre-theory markup command (cf.\ \secref{sec:markup-thy} and
+  \secref{sec:markup-thy}).  The @{command "end"} command concludes a
+  theory development; it has to be the very last command of any theory
+  file loaded in batch-mode.
+
+  \begin{rail}
+    'header' text
+    ;
+    'theory' name 'imports' (name +) uses? 'begin'
+    ;
+
+    uses: 'uses' ((name | parname) +);
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "header"}~@{text "text"}] provides plain text
+  markup just preceding the formal beginning of a theory.  In actual
+  document preparation the corresponding {\LaTeX} macro @{verbatim
+  "\\isamarkupheader"} may be redefined to produce chapter or section
+  headings.  See also \secref{sec:markup-thy} and
+  \secref{sec:markup-prf} for further markup commands.
+  
+  \item [@{command "theory"}~@{text "A \<IMPORTS> B\<^sub>1 \<dots>
+  B\<^sub>n \<BEGIN>"}] starts a new theory @{text A} based on the
+  merge of existing theories @{text "B\<^sub>1 \<dots> B\<^sub>n"}.
+  
+  Due to inclusion of several ancestors, the overall theory structure
+  emerging in an Isabelle session forms a directed acyclic graph
+  (DAG).  Isabelle's theory loader ensures that the sources
+  contributing to the development graph are always up-to-date.
+  Changed files are automatically reloaded when processing theory
+  headers.
+  
+  The optional @{keyword_def "uses"} specification declares additional
+  dependencies on extra files (usually ML sources).  Files will be
+  loaded immediately (as ML), unless the name is put in parentheses,
+  which merely documents the dependency to be resolved later in the
+  text (typically via explicit @{command_ref "use"} in the body text,
+  see \secref{sec:ML}).
+  
+  \item [@{command "end"}] concludes the current theory definition or
+  context switch.
+
+  \end{descr}
+*}
+
+
+subsection {* Markup commands \label{sec:markup-thy} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "chapter"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "section"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "subsection"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "subsubsection"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "text"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "text_raw"} & : & \isarkeep{local{\dsh}theory} \\
+  \end{matharray}
+
+  Apart from formal comments (see \secref{sec:comments}), markup
+  commands provide a structured way to insert text into the document
+  generated from a theory (see \cite{isabelle-sys} for more
+  information on Isabelle's document preparation tools).
+
+  \begin{rail}
+    ('chapter' | 'section' | 'subsection' | 'subsubsection' | 'text') target? text
+    ;
+    'text\_raw' text
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "chapter"}, @{command "section"}, @{command
+  "subsection"}, and @{command "subsubsection"}] mark chapter and
+  section headings.
+
+  \item [@{command "text"}] specifies paragraphs of plain text.
+
+  \item [@{command "text_raw"}] inserts {\LaTeX} source into the
+  output, without additional markup.  Thus the full range of document
+  manipulations becomes available.
+
+  \end{descr}
+
+  The @{text "text"} argument of these markup commands (except for
+  @{command "text_raw"}) may contain references to formal entities
+  (``antiquotations'', see also \secref{sec:antiq}).  These are
+  interpreted in the present theory context, or the named @{text
+  "target"}.
+
+  Any of these markup elements corresponds to a {\LaTeX} command with
+  the name prefixed by @{verbatim "\\isamarkup"}.  For the sectioning
+  commands this is a plain macro with a single argument, e.g.\
+  @{verbatim "\\isamarkupchapter{"}@{text "\<dots>"}@{verbatim "}"} for
+  @{command "chapter"}.  The @{command "text"} markup results in a
+  {\LaTeX} environment @{verbatim "\\begin{isamarkuptext}"}~@{text
+  "\<dots>"}~@{verbatim "\\end{isamarkuptext}"}, while @{command "text_raw"}
+  causes the text to be inserted directly into the {\LaTeX} source.
+
+  \medskip Additional markup commands are available for proofs (see
+  \secref{sec:markup-prf}).  Also note that the @{command_ref
+  "header"} declaration (see \secref{sec:begin-thy}) admits to insert
+  section markup just preceding the actual theory definition.
+*}
+
+
+subsection {* Type classes and sorts \label{sec:classes} *}
+
+text {*
+  \begin{matharray}{rcll}
+    @{command_def "classes"} & : & \isartrans{theory}{theory} \\
+    @{command_def "classrel"} & : & \isartrans{theory}{theory} & (axiomatic!) \\
+    @{command_def "defaultsort"} & : & \isartrans{theory}{theory} \\
+    @{command_def "class_deps"} & : & \isarkeep{theory~|~proof} \\
+  \end{matharray}
+
+  \begin{rail}
+    'classes' (classdecl +)
+    ;
+    'classrel' (nameref ('<' | subseteq) nameref + 'and')
+    ;
+    'defaultsort' sort
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "classes"}~@{text "c \<subseteq> c\<^sub>1, \<dots>, c\<^sub>n"}]
+  declares class @{text c} to be a subclass of existing classes @{text
+  "c\<^sub>1, \<dots>, c\<^sub>n"}.  Cyclic class structures are not permitted.
+
+  \item [@{command "classrel"}~@{text "c\<^sub>1 \<subseteq> c\<^sub>2"}] states
+  subclass relations between existing classes @{text "c\<^sub>1"} and
+  @{text "c\<^sub>2"}.  This is done axiomatically!  The @{command_ref
+  "instance"} command (see \secref{sec:axclass}) provides a way to
+  introduce proven class relations.
+
+  \item [@{command "defaultsort"}~@{text s}] makes sort @{text s} the
+  new default sort for any type variables given without sort
+  constraints.  Usually, the default sort would be only changed when
+  defining a new object-logic.
+
+  \item [@{command "class_deps"}] visualizes the subclass relation,
+  using Isabelle's graph browser tool (see also \cite{isabelle-sys}).
+
+  \end{descr}
+*}
+
+
+subsection {* Primitive types and type abbreviations \label{sec:types-pure} *}
+
+text {*
+  \begin{matharray}{rcll}
+    @{command_def "types"} & : & \isartrans{theory}{theory} \\
+    @{command_def "typedecl"} & : & \isartrans{theory}{theory} \\
+    @{command_def "nonterminals"} & : & \isartrans{theory}{theory} \\
+    @{command_def "arities"} & : & \isartrans{theory}{theory} & (axiomatic!) \\
+  \end{matharray}
+
+  \begin{rail}
+    'types' (typespec '=' type infix? +)
+    ;
+    'typedecl' typespec infix?
+    ;
+    'nonterminals' (name +)
+    ;
+    'arities' (nameref '::' arity +)
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "types"}~@{text "(\<alpha>\<^sub>1, \<dots>, \<alpha>\<^sub>n) t = \<tau>"}]
+  introduces \emph{type synonym} @{text "(\<alpha>\<^sub>1, \<dots>, \<alpha>\<^sub>n) t"}
+  for existing type @{text "\<tau>"}.  Unlike actual type definitions, as
+  are available in Isabelle/HOL for example, type synonyms are just
+  purely syntactic abbreviations without any logical significance.
+  Internally, type synonyms are fully expanded.
+  
+  \item [@{command "typedecl"}~@{text "(\<alpha>\<^sub>1, \<dots>, \<alpha>\<^sub>n) t"}]
+  declares a new type constructor @{text t}, intended as an actual
+  logical type (of the object-logic, if available).
+
+  \item [@{command "nonterminals"}~@{text c}] declares type
+  constructors @{text c} (without arguments) to act as purely
+  syntactic types, i.e.\ nonterminal symbols of Isabelle's inner
+  syntax of terms or types.
+
+  \item [@{command "arities"}~@{text "t :: (s\<^sub>1, \<dots>, s\<^sub>n)
+  s"}] augments Isabelle's order-sorted signature of types by new type
+  constructor arities.  This is done axiomatically!  The @{command_ref
+  "instance"} command (see \S\ref{sec:axclass}) provides a way to
+  introduce proven type arities.
+
+  \end{descr}
+*}
+
+
+subsection {* Primitive constants and definitions \label{sec:consts} *}
+
+text {*
+  Definitions essentially express abbreviations within the logic.  The
+  simplest form of a definition is @{text "c :: \<sigma> \<equiv> t"}, where @{text
+  c} is a newly declared constant.  Isabelle also allows derived forms
+  where the arguments of @{text c} appear on the left, abbreviating a
+  prefix of @{text \<lambda>}-abstractions, e.g.\ @{text "c \<equiv> \<lambda>x y. t"} may be
+  written more conveniently as @{text "c x y \<equiv> t"}.  Moreover,
+  definitions may be weakened by adding arbitrary pre-conditions:
+  @{text "A \<Longrightarrow> c x y \<equiv> t"}.
+
+  \medskip The built-in well-formedness conditions for definitional
+  specifications are:
+
+  \begin{itemize}
+
+  \item Arguments (on the left-hand side) must be distinct variables.
+
+  \item All variables on the right-hand side must also appear on the
+  left-hand side.
+
+  \item All type variables on the right-hand side must also appear on
+  the left-hand side; this prohibits @{text "0 :: nat \<equiv> length ([] ::
+  \<alpha> list)"} for example.
+
+  \item The definition must not be recursive.  Most object-logics
+  provide definitional principles that can be used to express
+  recursion safely.
+
+  \end{itemize}
+
+  Overloading means that a constant being declared as @{text "c :: \<alpha>
+  decl"} may be defined separately on type instances @{text "c ::
+  (\<beta>\<^sub>1, \<dots>, \<beta>\<^sub>n) t decl"} for each type constructor @{text
+  t}.  The right-hand side may mention overloaded constants
+  recursively at type instances corresponding to the immediate
+  argument types @{text "\<beta>\<^sub>1, \<dots>, \<beta>\<^sub>n"}.  Incomplete
+  specification patterns impose global constraints on all occurrences,
+  e.g.\ @{text "d :: \<alpha> \<times> \<alpha>"} on the left-hand side means that all
+  corresponding occurrences on some right-hand side need to be an
+  instance of this, general @{text "d :: \<alpha> \<times> \<beta>"} will be disallowed.
+
+  \begin{matharray}{rcl}
+    @{command_def "consts"} & : & \isartrans{theory}{theory} \\
+    @{command_def "defs"} & : & \isartrans{theory}{theory} \\
+    @{command_def "constdefs"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  \begin{rail}
+    'consts' ((name '::' type mixfix?) +)
+    ;
+    'defs' ('(' 'unchecked'? 'overloaded'? ')')? \\ (axmdecl prop +)
+    ;
+  \end{rail}
+
+  \begin{rail}
+    'constdefs' structs? (constdecl? constdef +)
+    ;
+
+    structs: '(' 'structure' (vars + 'and') ')'
+    ;
+    constdecl:  ((name '::' type mixfix | name '::' type | name mixfix) 'where'?) | name 'where'
+    ;
+    constdef: thmdecl? prop
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "consts"}~@{text "c :: \<sigma>"}] declares constant
+  @{text c} to have any instance of type scheme @{text \<sigma>}.  The
+  optional mixfix annotations may attach concrete syntax to the
+  constants declared.
+  
+  \item [@{command "defs"}~@{text "name: eqn"}] introduces @{text eqn}
+  as a definitional axiom for some existing constant.
+  
+  The @{text "(unchecked)"} option disables global dependency checks
+  for this definition, which is occasionally useful for exotic
+  overloading.  It is at the discretion of the user to avoid malformed
+  theory specifications!
+  
+  The @{text "(overloaded)"} option declares definitions to be
+  potentially overloaded.  Unless this option is given, a warning
+  message would be issued for any definitional equation with a more
+  special type than that of the corresponding constant declaration.
+  
+  \item [@{command "constdefs"}] provides a streamlined combination of
+  constants declarations and definitions: type-inference takes care of
+  the most general typing of the given specification (the optional
+  type constraint may refer to type-inference dummies ``@{verbatim
+  _}'' as usual).  The resulting type declaration needs to agree with
+  that of the specification; overloading is \emph{not} supported here!
+  
+  The constant name may be omitted altogether, if neither type nor
+  syntax declarations are given.  The canonical name of the
+  definitional axiom for constant @{text c} will be @{text c_def},
+  unless specified otherwise.  Also note that the given list of
+  specifications is processed in a strictly sequential manner, with
+  type-checking being performed independently.
+  
+  An optional initial context of @{text "(structure)"} declarations
+  admits use of indexed syntax, using the special symbol @{verbatim
+  "\<index>"} (printed as ``@{text "\<index>"}'').  The latter concept is
+  particularly useful with locales (see also \S\ref{sec:locale}).
+
+  \end{descr}
+*}
+
+
+subsection {* Syntax and translations \label{sec:syn-trans} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "syntax"} & : & \isartrans{theory}{theory} \\
+    @{command_def "no_syntax"} & : & \isartrans{theory}{theory} \\
+    @{command_def "translations"} & : & \isartrans{theory}{theory} \\
+    @{command_def "no_translations"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  \railalias{rightleftharpoons}{\isasymrightleftharpoons}
+  \railterm{rightleftharpoons}
+
+  \railalias{rightharpoonup}{\isasymrightharpoonup}
+  \railterm{rightharpoonup}
+
+  \railalias{leftharpoondown}{\isasymleftharpoondown}
+  \railterm{leftharpoondown}
+
+  \begin{rail}
+    ('syntax' | 'no\_syntax') mode? (constdecl +)
+    ;
+    ('translations' | 'no\_translations') (transpat ('==' | '=>' | '<=' | rightleftharpoons | rightharpoonup | leftharpoondown) transpat +)
+    ;
+
+    mode: ('(' ( name | 'output' | name 'output' ) ')')
+    ;
+    transpat: ('(' nameref ')')? string
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [@{command "syntax"}~@{text "(mode) decls"}] is similar to
+  @{command "consts"}~@{text decls}, except that the actual logical
+  signature extension is omitted.  Thus the context free grammar of
+  Isabelle's inner syntax may be augmented in arbitrary ways,
+  independently of the logic.  The @{text mode} argument refers to the
+  print mode that the grammar rules belong; unless the @{keyword_ref
+  "output"} indicator is given, all productions are added both to the
+  input and output grammar.
+  
+  \item [@{command "no_syntax"}~@{text "(mode) decls"}] removes
+  grammar declarations (and translations) resulting from @{text
+  decls}, which are interpreted in the same manner as for @{command
+  "syntax"} above.
+  
+  \item [@{command "translations"}~@{text rules}] specifies syntactic
+  translation rules (i.e.\ macros): parse~/ print rules (@{text "\<rightleftharpoons>"}),
+  parse rules (@{text "\<rightharpoonup>"}), or print rules (@{text "\<leftharpoondown>"}).
+  Translation patterns may be prefixed by the syntactic category to be
+  used for parsing; the default is @{text logic}.
+  
+  \item [@{command "no_translations"}~@{text rules}] removes syntactic
+  translation rules, which are interpreted in the same manner as for
+  @{command "translations"} above.
+
+  \end{descr}
+*}
+
+
+subsection {* Axioms and theorems \label{sec:axms-thms} *}
+
+text {*
+  \begin{matharray}{rcll}
+    @{command_def "axioms"} & : & \isartrans{theory}{theory} & (axiomatic!) \\
+    @{command_def "lemmas"} & : & \isarkeep{local{\dsh}theory} \\
+    @{command_def "theorems"} & : & isarkeep{local{\dsh}theory} \\
+  \end{matharray}
+
+  \begin{rail}
+    'axioms' (axmdecl prop +)
+    ;
+    ('lemmas' | 'theorems') target? (thmdef? thmrefs + 'and')
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [@{command "axioms"}~@{text "a: \<phi>"}] introduces arbitrary
+  statements as axioms of the meta-logic.  In fact, axioms are
+  ``axiomatic theorems'', and may be referred later just as any other
+  theorem.
+  
+  Axioms are usually only introduced when declaring new logical
+  systems.  Everyday work is typically done the hard way, with proper
+  definitions and proven theorems.
+  
+  \item [@{command "lemmas"}~@{text "a = b\<^sub>1 \<dots> b\<^sub>n"}]
+  retrieves and stores existing facts in the theory context, or the
+  specified target context (see also \secref{sec:target}).  Typical
+  applications would also involve attributes, to declare Simplifier
+  rules, for example.
+  
+  \item [@{command "theorems"}] is essentially the same as @{command
+  "lemmas"}, but marks the result as a different kind of facts.
+
+  \end{descr}
+*}
+
+
+subsection {* Name spaces *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "global"} & : & \isartrans{theory}{theory} \\
+    @{command_def "local"} & : & \isartrans{theory}{theory} \\
+    @{command_def "hide"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  \begin{rail}
+    'hide' ('(open)')? name (nameref + )
+    ;
+  \end{rail}
+
+  Isabelle organizes any kind of name declarations (of types,
+  constants, theorems etc.) by separate hierarchically structured name
+  spaces.  Normally the user does not have to control the behavior of
+  name spaces by hand, yet the following commands provide some way to
+  do so.
+
+  \begin{descr}
+
+  \item [@{command "global"} and @{command "local"}] change the
+  current name declaration mode.  Initially, theories start in
+  @{command "local"} mode, causing all names to be automatically
+  qualified by the theory name.  Changing this to @{command "global"}
+  causes all names to be declared without the theory prefix, until
+  @{command "local"} is declared again.
+  
+  Note that global names are prone to get hidden accidently later,
+  when qualified names of the same base name are introduced.
+  
+  \item [@{command "hide"}~@{text "space names"}] fully removes
+  declarations from a given name space (which may be @{text "class"},
+  @{text "type"}, @{text "const"}, or @{text "fact"}); with the @{text
+  "(open)"} option, only the base name is hidden.  Global
+  (unqualified) names may never be hidden.
+  
+  Note that hiding name space accesses has no impact on logical
+  declarations -- they remain valid internally.  Entities that are no
+  longer accessible to the user are printed with the special qualifier
+  ``@{text "??"}'' prefixed to the full internal name.
+
+  \end{descr}
+*}
+
+
+subsection {* Incorporating ML code \label{sec:ML} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "use"} & : & \isarkeep{theory~|~local{\dsh}theory} \\
+    @{command_def "ML"} & : & \isarkeep{theory~|~local{\dsh}theory} \\
+    @{command_def "ML_val"} & : & \isartrans{\cdot}{\cdot} \\
+    @{command_def "ML_command"} & : & \isartrans{\cdot}{\cdot} \\
+    @{command_def "setup"} & : & \isartrans{theory}{theory} \\
+    @{command_def "method_setup"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  \begin{rail}
+    'use' name
+    ;
+    ('ML' | 'ML\_val' | 'ML\_command' | 'setup') text
+    ;
+    'method\_setup' name '=' text text
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "use"}~@{text "file"}] reads and executes ML
+  commands from @{text "file"}.  The current theory context is passed
+  down to the ML toplevel and may be modified, using @{ML
+  "Context.>>"} or derived ML commands.  The file name is checked with
+  the @{keyword_ref "uses"} dependency declaration given in the theory
+  header (see also \secref{sec:begin-thy}).
+  
+  \item [@{command "ML"}~@{text "text"}] is similar to @{command
+  "use"}, but executes ML commands directly from the given @{text
+  "text"}.
+
+  \item [@{command "ML_val"} and @{command "ML_command"}] are
+  diagnostic versions of @{command "ML"}, which means that the context
+  may not be updated.  @{command "ML_val"} echos the bindings produced
+  at the ML toplevel, but @{command "ML_command"} is silent.
+  
+  \item [@{command "setup"}~@{text "text"}] changes the current theory
+  context by applying @{text "text"}, which refers to an ML expression
+  of type @{ML_type "theory -> theory"}.  This enables to initialize
+  any object-logic specific tools and packages written in ML, for
+  example.
+  
+  \item [@{command "method_setup"}~@{text "name = text description"}]
+  defines a proof method in the current theory.  The given @{text
+  "text"} has to be an ML expression of type @{ML_type "Args.src ->
+  Proof.context -> Proof.method"}.  Parsing concrete method syntax
+  from @{ML_type Args.src} input can be quite tedious in general.  The
+  following simple examples are for methods without any explicit
+  arguments, or a list of theorems, respectively.
+
+%FIXME proper antiquotations
+{\footnotesize
+\begin{verbatim}
+ Method.no_args (Method.METHOD (fn facts => foobar_tac))
+ Method.thms_args (fn thms => Method.METHOD (fn facts => foobar_tac))
+ Method.ctxt_args (fn ctxt => Method.METHOD (fn facts => foobar_tac))
+ Method.thms_ctxt_args (fn thms => fn ctxt =>
+    Method.METHOD (fn facts => foobar_tac))
+\end{verbatim}
+}
+
+  Note that mere tactic emulations may ignore the @{text facts}
+  parameter above.  Proper proof methods would do something
+  appropriate with the list of current facts, though.  Single-rule
+  methods usually do strict forward-chaining (e.g.\ by using @{ML
+  Drule.multi_resolves}), while automatic ones just insert the facts
+  using @{ML Method.insert_tac} before applying the main tactic.
+
+  \end{descr}
+*}
+
+
+subsection {* Syntax translation functions *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "parse_ast_translation"} & : & \isartrans{theory}{theory} \\
+    @{command_def "parse_translation"} & : & \isartrans{theory}{theory} \\
+    @{command_def "print_translation"} & : & \isartrans{theory}{theory} \\
+    @{command_def "typed_print_translation"} & : & \isartrans{theory}{theory} \\
+    @{command_def "print_ast_translation"} & : & \isartrans{theory}{theory} \\
+    @{command_def "token_translation"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  \begin{rail}
+  ( 'parse\_ast\_translation' | 'parse\_translation' | 'print\_translation' |
+    'typed\_print\_translation' | 'print\_ast\_translation' ) ('(advanced)')? text
+  ;
+
+  'token\_translation' text
+  ;
+  \end{rail}
+
+  Syntax translation functions written in ML admit almost arbitrary
+  manipulations of Isabelle's inner syntax.  Any of the above commands
+  have a single \railqtok{text} argument that refers to an ML
+  expression of appropriate type, which are as follows by default:
+
+%FIXME proper antiquotations
+\begin{ttbox}
+val parse_ast_translation   : (string * (ast list -> ast)) list
+val parse_translation       : (string * (term list -> term)) list
+val print_translation       : (string * (term list -> term)) list
+val typed_print_translation :
+  (string * (bool -> typ -> term list -> term)) list
+val print_ast_translation   : (string * (ast list -> ast)) list
+val token_translation       :
+  (string * string * (string -> string * real)) list
+\end{ttbox}
+
+  If the @{text "(advanced)"} option is given, the corresponding
+  translation functions may depend on the current theory or proof
+  context.  This allows to implement advanced syntax mechanisms, as
+  translations functions may refer to specific theory declarations or
+  auxiliary proof data.
+
+  See also \cite[\S8]{isabelle-ref} for more information on the
+  general concept of syntax transformations in Isabelle.
+
+%FIXME proper antiquotations
+\begin{ttbox}
+val parse_ast_translation:
+  (string * (Context.generic -> ast list -> ast)) list
+val parse_translation:
+  (string * (Context.generic -> term list -> term)) list
+val print_translation:
+  (string * (Context.generic -> term list -> term)) list
+val typed_print_translation:
+  (string * (Context.generic -> bool -> typ -> term list -> term)) list
+val print_ast_translation:
+  (string * (Context.generic -> ast list -> ast)) list
+\end{ttbox}
+*}
+
+
+subsection {* Oracles *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "oracle"} & : & \isartrans{theory}{theory} \\
+  \end{matharray}
+
+  The oracle interface promotes a given ML function @{ML_text
+  "theory -> T -> term"} to @{ML_text "theory -> T -> thm"}, for some type
+  @{ML_text T} given by the user.  This acts like an infinitary
+  specification of axioms -- there is no internal check of the
+  correctness of the results!  The inference kernel records oracle
+  invocations within the internal derivation object of theorems, and
+  the pretty printer attaches ``@{text "[!]"}'' to indicate results
+  that are not fully checked by Isabelle inferences.
+
+  \begin{rail}
+    'oracle' name '(' type ')' '=' text
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "oracle"}~@{text "name (type) = text"}] turns the
+  given ML expression @{text "text"} of type @{ML_text "{theory
+  ->"}~@{text "type"}~@{ML_text "-> term"} into an ML function
+  @{ML_text name} of type @{ML_text "{theory ->"}~@{text
+  "type"}~@{ML_text "-> thm"}.
+
+  \end{descr}
+*}
+
+
+section {* Proof commands *}
+
+text {*
+  Proof commands perform transitions of Isar/VM machine
+  configurations, which are block-structured, consisting of a stack of
+  nodes with three main components: logical proof context, current
+  facts, and open goals.  Isar/VM transitions are \emph{typed}
+  according to the following three different modes of operation:
+
+  \begin{descr}
+
+  \item [@{text "proof(prove)"}] means that a new goal has just been
+  stated that is now to be \emph{proven}; the next command may refine
+  it by some proof method, and enter a sub-proof to establish the
+  actual result.
+
+  \item [@{text "proof(state)"}] is like a nested theory mode: the
+  context may be augmented by \emph{stating} additional assumptions,
+  intermediate results etc.
+
+  \item [@{text "proof(chain)"}] is intermediate between @{text
+  "proof(state)"} and @{text "proof(prove)"}: existing facts (i.e.\
+  the contents of the special ``@{fact_ref this}'' register) have been
+  just picked up in order to be used when refining the goal claimed
+  next.
+
+  \end{descr}
+
+  The proof mode indicator may be read as a verb telling the writer
+  what kind of operation may be performed next.  The corresponding
+  typings of proof commands restricts the shape of well-formed proof
+  texts to particular command sequences.  So dynamic arrangements of
+  commands eventually turn out as static texts of a certain structure.
+  \Appref{ap:refcard} gives a simplified grammar of the overall
+  (extensible) language emerging that way.
+*}
+
+
+subsection {* Markup commands \label{sec:markup-prf} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "sect"} & : & \isartrans{proof}{proof} \\
+    @{command_def "subsect"} & : & \isartrans{proof}{proof} \\
+    @{command_def "subsubsect"} & : & \isartrans{proof}{proof} \\
+    @{command_def "txt"} & : & \isartrans{proof}{proof} \\
+    @{command_def "txt_raw"} & : & \isartrans{proof}{proof} \\
+  \end{matharray}
+
+  These markup commands for proof mode closely correspond to the ones
+  of theory mode (see \S\ref{sec:markup-thy}).
+
+  \begin{rail}
+    ('sect' | 'subsect' | 'subsubsect' | 'txt' | 'txt\_raw') text
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Context elements \label{sec:proof-context} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "fix"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "assume"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "presume"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "def"} & : & \isartrans{proof(state)}{proof(state)} \\
+  \end{matharray}
+
+  The logical proof context consists of fixed variables and
+  assumptions.  The former closely correspond to Skolem constants, or
+  meta-level universal quantification as provided by the Isabelle/Pure
+  logical framework.  Introducing some \emph{arbitrary, but fixed}
+  variable via ``@{command "fix"}~@{text x} results in a local value
+  that may be used in the subsequent proof as any other variable or
+  constant.  Furthermore, any result @{text "\<turnstile> \<phi>[x]"} exported from
+  the context will be universally closed wrt.\ @{text x} at the
+  outermost level: @{text "\<turnstile> \<And>x. \<phi>[x]"} (this is expressed in normal
+  form using Isabelle's meta-variables).
+
+  Similarly, introducing some assumption @{text \<chi>} has two effects.
+  On the one hand, a local theorem is created that may be used as a
+  fact in subsequent proof steps.  On the other hand, any result
+  @{text "\<chi> \<turnstile> \<phi>"} exported from the context becomes conditional wrt.\
+  the assumption: @{text "\<turnstile> \<chi> \<Longrightarrow> \<phi>"}.  Thus, solving an enclosing goal
+  using such a result would basically introduce a new subgoal stemming
+  from the assumption.  How this situation is handled depends on the
+  version of assumption command used: while @{command "assume"}
+  insists on solving the subgoal by unification with some premise of
+  the goal, @{command "presume"} leaves the subgoal unchanged in order
+  to be proved later by the user.
+
+  Local definitions, introduced by ``@{command "def"}~@{text "x \<equiv>
+  t"}'', are achieved by combining ``@{command "fix"}~@{text x}'' with
+  another version of assumption that causes any hypothetical equation
+  @{text "x \<equiv> t"} to be eliminated by the reflexivity rule.  Thus,
+  exporting some result @{text "x \<equiv> t \<turnstile> \<phi>[x]"} yields @{text "\<turnstile>
+  \<phi>[t]"}.
+
+  \railalias{equiv}{\isasymequiv}
+  \railterm{equiv}
+
+  \begin{rail}
+    'fix' (vars + 'and')
+    ;
+    ('assume' | 'presume') (props + 'and')
+    ;
+    'def' (def + 'and')
+    ;
+    def: thmdecl? \\ name ('==' | equiv) term termpat?
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [@{command "fix"}~@{text x}] introduces a local variable
+  @{text x} that is \emph{arbitrary, but fixed.}
+  
+  \item [@{command "assume"}~@{text "a: \<phi>"} and @{command
+  "presume"}~@{text "a: \<phi>"}] introduce a local fact @{text "\<phi> \<turnstile> \<phi>"} by
+  assumption.  Subsequent results applied to an enclosing goal (e.g.\
+  by @{command_ref "show"}) are handled as follows: @{command
+  "assume"} expects to be able to unify with existing premises in the
+  goal, while @{command "presume"} leaves @{text \<phi>} as new subgoals.
+  
+  Several lists of assumptions may be given (separated by
+  @{keyword_ref "and"}; the resulting list of current facts consists
+  of all of these concatenated.
+  
+  \item [@{command "def"}~@{text "x \<equiv> t"}] introduces a local
+  (non-polymorphic) definition.  In results exported from the context,
+  @{text x} is replaced by @{text t}.  Basically, ``@{command
+  "def"}~@{text "x \<equiv> t"}'' abbreviates ``@{command "fix"}~@{text
+  x}~@{command "assume"}~@{text "x \<equiv> t"}'', with the resulting
+  hypothetical equation solved by reflexivity.
+  
+  The default name for the definitional equation is @{text x_def}.
+  Several simultaneous definitions may be given at the same time.
+
+  \end{descr}
+
+  The special name @{fact_ref prems} refers to all assumptions of the
+  current context as a list of theorems.  This feature should be used
+  with great care!  It is better avoided in final proof texts.
+*}
+
+
+subsection {* Facts and forward chaining *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "note"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "then"} & : & \isartrans{proof(state)}{proof(chain)} \\
+    @{command_def "from"} & : & \isartrans{proof(state)}{proof(chain)} \\
+    @{command_def "with"} & : & \isartrans{proof(state)}{proof(chain)} \\
+    @{command_def "using"} & : & \isartrans{proof(prove)}{proof(prove)} \\
+    @{command_def "unfolding"} & : & \isartrans{proof(prove)}{proof(prove)} \\
+  \end{matharray}
+
+  New facts are established either by assumption or proof of local
+  statements.  Any fact will usually be involved in further proofs,
+  either as explicit arguments of proof methods, or when forward
+  chaining towards the next goal via @{command "then"} (and variants);
+  @{command "from"} and @{command "with"} are composite forms
+  involving @{command "note"}.  The @{command "using"} elements
+  augments the collection of used facts \emph{after} a goal has been
+  stated.  Note that the special theorem name @{fact_ref this} refers
+  to the most recently established facts, but only \emph{before}
+  issuing a follow-up claim.
+
+  \begin{rail}
+    'note' (thmdef? thmrefs + 'and')
+    ;
+    ('from' | 'with' | 'using' | 'unfolding') (thmrefs + 'and')
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "note"}~@{text "a = b\<^sub>1 \<dots> b\<^sub>n"}]
+  recalls existing facts @{text "b\<^sub>1, \<dots>, b\<^sub>n"}, binding
+  the result as @{text a}.  Note that attributes may be involved as
+  well, both on the left and right hand sides.
+
+  \item [@{command "then"}] indicates forward chaining by the current
+  facts in order to establish the goal to be claimed next.  The
+  initial proof method invoked to refine that will be offered the
+  facts to do ``anything appropriate'' (see also
+  \secref{sec:proof-steps}).  For example, method @{method_ref rule}
+  (see \secref{sec:pure-meth-att}) would typically do an elimination
+  rather than an introduction.  Automatic methods usually insert the
+  facts into the goal state before operation.  This provides a simple
+  scheme to control relevance of facts in automated proof search.
+  
+  \item [@{command "from"}~@{text b}] abbreviates ``@{command
+  "note"}~@{text b}~@{command "then"}''; thus @{command "then"} is
+  equivalent to ``@{command "from"}~@{text this}''.
+  
+  \item [@{command "with"}~@{text "b\<^sub>1 \<dots> b\<^sub>n"}]
+  abbreviates ``@{command "from"}~@{text "b\<^sub>1 \<dots> b\<^sub>n \<AND>
+  this"}''; thus the forward chaining is from earlier facts together
+  with the current ones.
+  
+  \item [@{command "using"}~@{text "b\<^sub>1 \<dots> b\<^sub>n"}] augments
+  the facts being currently indicated for use by a subsequent
+  refinement step (such as @{command_ref "apply"} or @{command_ref
+  "proof"}).
+  
+  \item [@{command "unfolding"}~@{text "b\<^sub>1 \<dots> b\<^sub>n"}] is
+  structurally similar to @{command "using"}, but unfolds definitional
+  equations @{text "b\<^sub>1, \<dots> b\<^sub>n"} throughout the goal state
+  and facts.
+
+  \end{descr}
+
+  Forward chaining with an empty list of theorems is the same as not
+  chaining at all.  Thus ``@{command "from"}~@{text nothing}'' has no
+  effect apart from entering @{text "prove(chain)"} mode, since
+  @{fact_ref nothing} is bound to the empty list of theorems.
+
+  Basic proof methods (such as @{method_ref rule}) expect multiple
+  facts to be given in their proper order, corresponding to a prefix
+  of the premises of the rule involved.  Note that positions may be
+  easily skipped using something like @{command "from"}~@{text "_
+  \<AND> a \<AND> b"}, for example.  This involves the trivial rule
+  @{text "PROP \<psi> \<Longrightarrow> PROP \<psi>"}, which is bound in Isabelle/Pure as
+  ``@{fact_ref "_"}'' (underscore).
+
+  Automated methods (such as @{method simp} or @{method auto}) just
+  insert any given facts before their usual operation.  Depending on
+  the kind of procedure involved, the order of facts is less
+  significant here.
+*}
+
+
+subsection {* Goal statements \label{sec:goals} *}
+
+text {*
+  \begin{matharray}{rcl}
+    \isarcmd{lemma} & : & \isartrans{local{\dsh}theory}{proof(prove)} \\
+    \isarcmd{theorem} & : & \isartrans{local{\dsh}theory}{proof(prove)} \\
+    \isarcmd{corollary} & : & \isartrans{local{\dsh}theory}{proof(prove)} \\
+    \isarcmd{have} & : & \isartrans{proof(state) ~|~ proof(chain)}{proof(prove)} \\
+    \isarcmd{show} & : & \isartrans{proof(state) ~|~ proof(chain)}{proof(prove)} \\
+    \isarcmd{hence} & : & \isartrans{proof(state)}{proof(prove)} \\
+    \isarcmd{thus} & : & \isartrans{proof(state)}{proof(prove)} \\
+    \isarcmd{print_statement}^* & : & \isarkeep{theory~|~proof} \\
+  \end{matharray}
+
+  From a theory context, proof mode is entered by an initial goal
+  command such as @{command "lemma"}, @{command "theorem"}, or
+  @{command "corollary"}.  Within a proof, new claims may be
+  introduced locally as well; four variants are available here to
+  indicate whether forward chaining of facts should be performed
+  initially (via @{command_ref "then"}), and whether the final result
+  is meant to solve some pending goal.
+
+  Goals may consist of multiple statements, resulting in a list of
+  facts eventually.  A pending multi-goal is internally represented as
+  a meta-level conjunction (printed as @{text "&&"}), which is usually
+  split into the corresponding number of sub-goals prior to an initial
+  method application, via @{command_ref "proof"}
+  (\secref{sec:proof-steps}) or @{command_ref "apply"}
+  (\secref{sec:tactic-commands}).  The @{method_ref induct} method
+  covered in \secref{sec:cases-induct} acts on multiple claims
+  simultaneously.
+
+  Claims at the theory level may be either in short or long form.  A
+  short goal merely consists of several simultaneous propositions
+  (often just one).  A long goal includes an explicit context
+  specification for the subsequent conclusion, involving local
+  parameters and assumptions.  Here the role of each part of the
+  statement is explicitly marked by separate keywords (see also
+  \secref{sec:locale}); the local assumptions being introduced here
+  are available as @{fact_ref assms} in the proof.  Moreover, there
+  are two kinds of conclusions: @{element_def "shows"} states several
+  simultaneous propositions (essentially a big conjunction), while
+  @{element_def "obtains"} claims several simultaneous simultaneous
+  contexts of (essentially a big disjunction of eliminated parameters
+  and assumptions, cf.\ \secref{sec:obtain}).
+
+  \begin{rail}
+    ('lemma' | 'theorem' | 'corollary') target? (goal | longgoal)
+    ;
+    ('have' | 'show' | 'hence' | 'thus') goal
+    ;
+    'print\_statement' modes? thmrefs
+    ;
+  
+    goal: (props + 'and')
+    ;
+    longgoal: thmdecl? (contextelem *) conclusion
+    ;
+    conclusion: 'shows' goal | 'obtains' (parname? case + '|')
+    ;
+    case: (vars + 'and') 'where' (props + 'and')
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [@{command "lemma"}~@{text "a: \<phi>"}] enters proof mode with
+  @{text \<phi>} as main goal, eventually resulting in some fact @{text "\<turnstile>
+  \<phi>"} to be put back into the target context.  An additional
+  \railnonterm{context} specification may build up an initial proof
+  context for the subsequent claim; this includes local definitions
+  and syntax as well, see the definition of @{syntax contextelem} in
+  \secref{sec:locale}.
+  
+  \item [@{command "theorem"}~@{text "a: \<phi>"} and @{command
+  "corollary"}~@{text "a: \<phi>"}] are essentially the same as @{command
+  "lemma"}~@{text "a: \<phi>"}, but the facts are internally marked as
+  being of a different kind.  This discrimination acts like a formal
+  comment.
+  
+  \item [@{command "have"}~@{text "a: \<phi>"}] claims a local goal,
+  eventually resulting in a fact within the current logical context.
+  This operation is completely independent of any pending sub-goals of
+  an enclosing goal statements, so @{command "have"} may be freely
+  used for experimental exploration of potential results within a
+  proof body.
+  
+  \item [@{command "show"}~@{text "a: \<phi>"}] is like @{command
+  "have"}~@{text "a: \<phi>"} plus a second stage to refine some pending
+  sub-goal for each one of the finished result, after having been
+  exported into the corresponding context (at the head of the
+  sub-proof of this @{command "show"} command).
+  
+  To accommodate interactive debugging, resulting rules are printed
+  before being applied internally.  Even more, interactive execution
+  of @{command "show"} predicts potential failure and displays the
+  resulting error as a warning beforehand.  Watch out for the
+  following message:
+
+  %FIXME proper antiquitation
+  \begin{ttbox}
+  Problem! Local statement will fail to solve any pending goal
+  \end{ttbox}
+  
+  \item [@{command "hence"}] abbreviates ``@{command "then"}~@{command
+  "have"}'', i.e.\ claims a local goal to be proven by forward
+  chaining the current facts.  Note that @{command "hence"} is also
+  equivalent to ``@{command "from"}~@{text this}~@{command "have"}''.
+  
+  \item [@{command "thus"}] abbreviates ``@{command "then"}~@{command
+  "show"}''.  Note that @{command "thus"} is also equivalent to
+  ``@{command "from"}~@{text this}~@{command "show"}''.
+  
+  \item [@{command "print_statement"}~@{text a}] prints facts from the
+  current theory or proof context in long statement form, according to
+  the syntax for @{command "lemma"} given above.
+
+  \end{descr}
+
+  Any goal statement causes some term abbreviations (such as
+  @{variable_ref "?thesis"}) to be bound automatically, see also
+  \secref{sec:term-abbrev}.  Furthermore, the local context of a
+  (non-atomic) goal is provided via the @{case_ref rule_context} case.
+
+  The optional case names of @{element_ref "obtains"} have a twofold
+  meaning: (1) during the of this claim they refer to the the local
+  context introductions, (2) the resulting rule is annotated
+  accordingly to support symbolic case splits when used with the
+  @{method_ref cases} method (cf.  \secref{sec:cases-induct}).
+
+  \medskip
+
+  \begin{warn}
+    Isabelle/Isar suffers theory-level goal statements to contain
+    \emph{unbound schematic variables}, although this does not conform
+    to the aim of human-readable proof documents!  The main problem
+    with schematic goals is that the actual outcome is usually hard to
+    predict, depending on the behavior of the proof methods applied
+    during the course of reasoning.  Note that most semi-automated
+    methods heavily depend on several kinds of implicit rule
+    declarations within the current theory context.  As this would
+    also result in non-compositional checking of sub-proofs,
+    \emph{local goals} are not allowed to be schematic at all.
+    Nevertheless, schematic goals do have their use in Prolog-style
+    interactive synthesis of proven results, usually by stepwise
+    refinement via emulation of traditional Isabelle tactic scripts
+    (see also \secref{sec:tactic-commands}).  In any case, users
+    should know what they are doing.
+  \end{warn}
+*}
+
+
+subsection {* Initial and terminal proof steps \label{sec:proof-steps} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "proof"} & : & \isartrans{proof(prove)}{proof(state)} \\
+    @{command_def "qed"} & : & \isartrans{proof(state)}{proof(state) ~|~ theory} \\
+    @{command_def "by"} & : & \isartrans{proof(prove)}{proof(state) ~|~ theory} \\
+    @{command_def ".."} & : & \isartrans{proof(prove)}{proof(state) ~|~ theory} \\
+    @{command_def "."} & : & \isartrans{proof(prove)}{proof(state) ~|~ theory} \\
+    @{command_def "sorry"} & : & \isartrans{proof(prove)}{proof(state) ~|~ theory} \\
+  \end{matharray}
+
+  Arbitrary goal refinement via tactics is considered harmful.
+  Structured proof composition in Isar admits proof methods to be
+  invoked in two places only.
+
+  \begin{enumerate}
+
+  \item An \emph{initial} refinement step @{command_ref
+  "proof"}~@{text "m\<^sub>1"} reduces a newly stated goal to a number
+  of sub-goals that are to be solved later.  Facts are passed to
+  @{text "m\<^sub>1"} for forward chaining, if so indicated by @{text
+  "proof(chain)"} mode.
+  
+  \item A \emph{terminal} conclusion step @{command_ref "qed"}~@{text
+  "m\<^sub>2"} is intended to solve remaining goals.  No facts are
+  passed to @{text "m\<^sub>2"}.
+
+  \end{enumerate}
+
+  The only other (proper) way to affect pending goals in a proof body
+  is by @{command_ref "show"}, which involves an explicit statement of
+  what is to be solved eventually.  Thus we avoid the fundamental
+  problem of unstructured tactic scripts that consist of numerous
+  consecutive goal transformations, with invisible effects.
+
+  \medskip As a general rule of thumb for good proof style, initial
+  proof methods should either solve the goal completely, or constitute
+  some well-understood reduction to new sub-goals.  Arbitrary
+  automatic proof tools that are prone leave a large number of badly
+  structured sub-goals are no help in continuing the proof document in
+  an intelligible manner.
+
+  Unless given explicitly by the user, the default initial method is
+  ``@{method_ref rule}'', which applies a single standard elimination
+  or introduction rule according to the topmost symbol involved.
+  There is no separate default terminal method.  Any remaining goals
+  are always solved by assumption in the very last step.
+
+  \begin{rail}
+    'proof' method?
+    ;
+    'qed' method?
+    ;
+    'by' method method?
+    ;
+    ('.' | '..' | 'sorry')
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [@{command "proof"}~@{text "m\<^sub>1"}] refines the goal by
+  proof method @{text "m\<^sub>1"}; facts for forward chaining are
+  passed if so indicated by @{text "proof(chain)"} mode.
+  
+  \item [@{command "qed"}~@{text "m\<^sub>2"}] refines any remaining
+  goals by proof method @{text "m\<^sub>2"} and concludes the
+  sub-proof by assumption.  If the goal had been @{text "show"} (or
+  @{text "thus"}), some pending sub-goal is solved as well by the rule
+  resulting from the result \emph{exported} into the enclosing goal
+  context.  Thus @{text "qed"} may fail for two reasons: either @{text
+  "m\<^sub>2"} fails, or the resulting rule does not fit to any
+  pending goal\footnote{This includes any additional ``strong''
+  assumptions as introduced by @{text "assume"}.} of the enclosing
+  context.  Debugging such a situation might involve temporarily
+  changing @{command "show"} into @{command "have"}, or weakening the
+  local context by replacing occurrences of @{command "assume"} by
+  @{command "presume"}.
+  
+  \item [@{command "by"}~@{text "m\<^sub>1 m\<^sub>2"}] is a
+  \emph{terminal proof}\index{proof!terminal}; it abbreviates
+  @{command "proof"}~@{text "m\<^sub>1"}~@{text "qed"}~@{text
+  "m\<^sub>2"}, but with backtracking across both methods.  Debugging
+  an unsuccessful @{command "by"}~@{text "m\<^sub>1 m\<^sub>2"}
+  command can be done by expanding its definition; in many cases
+  @{command "proof"}~@{text "m\<^sub>1"} (or even @{text
+  "apply"}~@{text "m\<^sub>1"}) is already sufficient to see the
+  problem.
+
+  \item [``@{command ".."}''] is a \emph{default
+  proof}\index{proof!default}; it abbreviates @{command "by"}~@{text
+  "rule"}.
+
+  \item [``@{command "."}''] is a \emph{trivial
+  proof}\index{proof!trivial}; it abbreviates @{command "by"}~@{text
+  "this"}.
+  
+  \item [@{command "sorry"}] is a \emph{fake proof}\index{proof!fake}
+  pretending to solve the pending claim without further ado.  This
+  only works in interactive development, or if the @{ML
+  quick_and_dirty} flag is enabled (in ML).  Facts emerging from fake
+  proofs are not the real thing.  Internally, each theorem container
+  is tainted by an oracle invocation, which is indicated as ``@{text
+  "[!]"}'' in the printed result.
+  
+  The most important application of @{command "sorry"} is to support
+  experimentation and top-down proof development.
+
+  \end{descr}
+*}
+
+
+subsection {* Fundamental methods and attributes \label{sec:pure-meth-att} *}
+
+text {*
+  The following proof methods and attributes refer to basic logical
+  operations of Isar.  Further methods and attributes are provided by
+  several generic and object-logic specific tools and packages (see
+  \chref{ch:gen-tools} and \chref{ch:logics}).
+
+  \begin{matharray}{rcl}
+    @{method_def "-"} & : & \isarmeth \\
+    @{method_def "fact"} & : & \isarmeth \\
+    @{method_def "assumption"} & : & \isarmeth \\
+    @{method_def "this"} & : & \isarmeth \\
+    @{method_def "rule"} & : & \isarmeth \\
+    @{method_def "iprover"} & : & \isarmeth \\[0.5ex]
+    @{attribute_def "intro"} & : & \isaratt \\
+    @{attribute_def "elim"} & : & \isaratt \\
+    @{attribute_def "dest"} & : & \isaratt \\
+    @{attribute_def "rule"} & : & \isaratt \\[0.5ex]
+    @{attribute_def "OF"} & : & \isaratt \\
+    @{attribute_def "of"} & : & \isaratt \\
+    @{attribute_def "where"} & : & \isaratt \\
+  \end{matharray}
+
+  \begin{rail}
+    'fact' thmrefs?
+    ;
+    'rule' thmrefs?
+    ;
+    'iprover' ('!' ?) (rulemod *)
+    ;
+    rulemod: ('intro' | 'elim' | 'dest') ((('!' | () | '?') nat?) | 'del') ':' thmrefs
+    ;
+    ('intro' | 'elim' | 'dest') ('!' | () | '?') nat?
+    ;
+    'rule' 'del'
+    ;
+    'OF' thmrefs
+    ;
+    'of' insts ('concl' ':' insts)?
+    ;
+    'where' ((name | var | typefree | typevar) '=' (type | term) * 'and')
+    ;
+  \end{rail}
+
+  \begin{descr}
+  
+  \item [``@{method "-"}''] does nothing but insert the forward
+  chaining facts as premises into the goal.  Note that command
+  @{command_ref "proof"} without any method actually performs a single
+  reduction step using the @{method_ref rule} method; thus a plain
+  \emph{do-nothing} proof step would be ``@{command "proof"}~@{text
+  "-"}'' rather than @{command "proof"} alone.
+  
+  \item [@{method "fact"}~@{text "a\<^sub>1 \<dots> a\<^sub>n"}] composes
+  some fact from @{text "a\<^sub>1, \<dots>, a\<^sub>n"} (or implicitly from
+  the current proof context) modulo unification of schematic type and
+  term variables.  The rule structure is not taken into account, i.e.\
+  meta-level implication is considered atomic.  This is the same
+  principle underlying literal facts (cf.\ \secref{sec:syn-att}):
+  ``@{command "have"}~@{text "\<phi>"}~@{command "by"}~@{text fact}'' is
+  equivalent to ``@{command "note"}~@{verbatim "`"}@{text \<phi>}@{verbatim
+  "`"}'' provided that @{text "\<turnstile> \<phi>"} is an instance of some known
+  @{text "\<turnstile> \<phi>"} in the proof context.
+  
+  \item [@{method assumption}] solves some goal by a single assumption
+  step.  All given facts are guaranteed to participate in the
+  refinement; this means there may be only 0 or 1 in the first place.
+  Recall that @{command "qed"} (\secref{sec:proof-steps}) already
+  concludes any remaining sub-goals by assumption, so structured
+  proofs usually need not quote the @{method assumption} method at
+  all.
+  
+  \item [@{method this}] applies all of the current facts directly as
+  rules.  Recall that ``@{command "."}'' (dot) abbreviates ``@{command
+  "by"}~@{text this}''.
+  
+  \item [@{method rule}~@{text "a\<^sub>1 \<dots> a\<^sub>n"}] applies some
+  rule given as argument in backward manner; facts are used to reduce
+  the rule before applying it to the goal.  Thus @{method rule}
+  without facts is plain introduction, while with facts it becomes
+  elimination.
+  
+  When no arguments are given, the @{method rule} method tries to pick
+  appropriate rules automatically, as declared in the current context
+  using the @{attribute intro}, @{attribute elim}, @{attribute dest}
+  attributes (see below).  This is the default behavior of @{command
+  "proof"} and ``@{command ".."}'' (double-dot) steps (see
+  \secref{sec:proof-steps}).
+  
+  \item [@{method iprover}] performs intuitionistic proof search,
+  depending on specifically declared rules from the context, or given
+  as explicit arguments.  Chained facts are inserted into the goal
+  before commencing proof search; ``@{method iprover}@{text "!"}'' 
+  means to include the current @{fact prems} as well.
+  
+  Rules need to be classified as @{attribute intro}, @{attribute
+  elim}, or @{attribute dest}; here the ``@{text "!"} indicator refers
+  to ``safe'' rules, which may be applied aggressively (without
+  considering back-tracking later).  Rules declared with ``@{text
+  "?"}'' are ignored in proof search (the single-step @{method rule}
+  method still observes these).  An explicit weight annotation may be
+  given as well; otherwise the number of rule premises will be taken
+  into account here.
+  
+  \item [@{attribute intro}, @{attribute elim}, and @{attribute dest}]
+  declare introduction, elimination, and destruct rules, to be used
+  with the @{method rule} and @{method iprover} methods.  Note that
+  the latter will ignore rules declared with ``@{text "?"}'', while
+  ``@{text "!"}''  are used most aggressively.
+  
+  The classical reasoner (see \secref{sec:classical}) introduces its
+  own variants of these attributes; use qualified names to access the
+  present versions of Isabelle/Pure, i.e.\ @{attribute "Pure.intro"}.
+  
+  \item [@{attribute rule}~@{text del}] undeclares introduction,
+  elimination, or destruct rules.
+  
+  \item [@{attribute OF}~@{text "a\<^sub>1 \<dots> a\<^sub>n"}] applies some
+  theorem to all of the given rules @{text "a\<^sub>1, \<dots>, a\<^sub>n"}
+  (in parallel).  This corresponds to the @{ML "op MRS"} operation in
+  ML, but note the reversed order.  Positions may be effectively
+  skipped by including ``@{verbatim _}'' (underscore) as argument.
+  
+  \item [@{attribute of}~@{text "t\<^sub>1 \<dots> t\<^sub>n"}] performs
+  positional instantiation of term variables.  The terms @{text
+  "t\<^sub>1, \<dots>, t\<^sub>n"} are substituted for any schematic
+  variables occurring in a theorem from left to right; ``@{verbatim
+  _}'' (underscore) indicates to skip a position.  Arguments following
+  a ``@{keyword "concl"}@{text ":"}'' specification refer to positions
+  of the conclusion of a rule.
+  
+  \item [@{attribute "where"}~@{text "x\<^sub>1 = t\<^sub>1 \<AND> \<dots>
+  \<AND> x\<^sub>n = t\<^sub>n"}] performs named instantiation of
+  schematic type and term variables occurring in a theorem.  Schematic
+  variables have to be specified on the left-hand side (e.g.\ @{text
+  "?x1.3"}).  The question mark may be omitted if the variable name is
+  a plain identifier without index.  As type instantiations are
+  inferred from term instantiations, explicit type instantiations are
+  seldom necessary.
+
+  \end{descr}
+*}
+
+
+subsection {* Term abbreviations \label{sec:term-abbrev} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "let"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{keyword_def "is"} & : & syntax \\
+  \end{matharray}
+
+  Abbreviations may be either bound by explicit @{command "let"}@{text
+  "p \<equiv> t"} statements, or by annotating assumptions or goal statements
+  with a list of patterns ``@{text "\<IS> p\<^sub>1 \<dots> p\<^sub>n"}''.
+  In both cases, higher-order matching is invoked to bind
+  extra-logical term variables, which may be either named schematic
+  variables of the form @{text ?x}, or nameless dummies ``@{variable
+  _}'' (underscore). Note that in the @{command "let"} form the
+  patterns occur on the left-hand side, while the @{keyword "is"}
+  patterns are in postfix position.
+
+  Polymorphism of term bindings is handled in Hindley-Milner style,
+  similar to ML.  Type variables referring to local assumptions or
+  open goal statements are \emph{fixed}, while those of finished
+  results or bound by @{command "let"} may occur in \emph{arbitrary}
+  instances later.  Even though actual polymorphism should be rarely
+  used in practice, this mechanism is essential to achieve proper
+  incremental type-inference, as the user proceeds to build up the
+  Isar proof text from left to right.
+
+  \medskip Term abbreviations are quite different from local
+  definitions as introduced via @{command "def"} (see
+  \secref{sec:proof-context}).  The latter are visible within the
+  logic as actual equations, while abbreviations disappear during the
+  input process just after type checking.  Also note that @{command
+  "def"} does not support polymorphism.
+
+  \begin{rail}
+    'let' ((term + 'and') '=' term + 'and')
+    ;  
+  \end{rail}
+
+  The syntax of @{keyword "is"} patterns follows \railnonterm{termpat}
+  or \railnonterm{proppat} (see \secref{sec:term-decls}).
+
+  \begin{descr}
+
+  \item [@{command "let"}~@{text "p\<^sub>1 = t\<^sub>1 \<AND>
+  \<dots>p\<^sub>n = t\<^sub>n"}] binds any text variables in patterns
+  @{text "p\<^sub>1, \<dots>, p\<^sub>n"} by simultaneous higher-order
+  matching against terms @{text "t\<^sub>1, \<dots>, t\<^sub>n"}.
+
+  \item [@{text "(\<IS> p\<^sub>1 \<dots> p\<^sub>n)"}] resembles @{command
+  "let"}, but matches @{text "p\<^sub>1, \<dots>, p\<^sub>n"} against the
+  preceding statement.  Also note that @{keyword "is"} is not a
+  separate command, but part of others (such as @{command "assume"},
+  @{command "have"} etc.).
+
+  \end{descr}
+
+  Some \emph{implicit} term abbreviations\index{term abbreviations}
+  for goals and facts are available as well.  For any open goal,
+  @{variable_ref thesis} refers to its object-level statement,
+  abstracted over any meta-level parameters (if present).  Likewise,
+  @{variable_ref this} is bound for fact statements resulting from
+  assumptions or finished goals.  In case @{variable this} refers to
+  an object-logic statement that is an application @{text "f t"}, then
+  @{text t} is bound to the special text variable ``@{variable "\<dots>"}''
+  (three dots).  The canonical application of this convenience are
+  calculational proofs (see \secref{sec:calculation}).
+*}
+
+
+subsection {* Block structure *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "next"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "{"} & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "}"} & : & \isartrans{proof(state)}{proof(state)} \\
+  \end{matharray}
+
+  While Isar is inherently block-structured, opening and closing
+  blocks is mostly handled rather casually, with little explicit
+  user-intervention.  Any local goal statement automatically opens
+  \emph{two} internal blocks, which are closed again when concluding
+  the sub-proof (by @{command "qed"} etc.).  Sections of different
+  context within a sub-proof may be switched via @{command "next"},
+  which is just a single block-close followed by block-open again.
+  The effect of @{command "next"} is to reset the local proof context;
+  there is no goal focus involved here!
+
+  For slightly more advanced applications, there are explicit block
+  parentheses as well.  These typically achieve a stronger forward
+  style of reasoning.
+
+  \begin{descr}
+
+  \item [@{command "next"}] switches to a fresh block within a
+  sub-proof, resetting the local context to the initial one.
+
+  \item [@{command "{"} and @{command "}"}] explicitly open and close
+  blocks.  Any current facts pass through ``@{command "{"}''
+  unchanged, while ``@{command "}"}'' causes any result to be
+  \emph{exported} into the enclosing context.  Thus fixed variables
+  are generalized, assumptions discharged, and local definitions
+  unfolded (cf.\ \secref{sec:proof-context}).  There is no difference
+  of @{command "assume"} and @{command "presume"} in this mode of
+  forward reasoning --- in contrast to plain backward reasoning with
+  the result exported at @{command "show"} time.
+
+  \end{descr}
+*}
+
+
+subsection {* Emulating tactic scripts \label{sec:tactic-commands} *}
+
+text {*
+  The Isar provides separate commands to accommodate tactic-style
+  proof scripts within the same system.  While being outside the
+  orthodox Isar proof language, these might come in handy for
+  interactive exploration and debugging, or even actual tactical proof
+  within new-style theories (to benefit from document preparation, for
+  example).  See also \secref{sec:tactics} for actual tactics, that
+  have been encapsulated as proof methods.  Proper proof methods may
+  be used in scripts, too.
+
+  \begin{matharray}{rcl}
+    @{command_def "apply"}^* & : & \isartrans{proof(prove)}{proof(prove)} \\
+    @{command_def "apply_end"}^* & : & \isartrans{proof(state)}{proof(state)} \\
+    @{command_def "done"}^* & : & \isartrans{proof(prove)}{proof(state)} \\
+    @{command_def "defer"}^* & : & \isartrans{proof}{proof} \\
+    @{command_def "prefer"}^* & : & \isartrans{proof}{proof} \\
+    @{command_def "back"}^* & : & \isartrans{proof}{proof} \\
+  \end{matharray}
+
+  \begin{rail}
+    ( 'apply' | 'apply\_end' ) method
+    ;
+    'defer' nat?
+    ;
+    'prefer' nat
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "apply"}~@{text m}] applies proof method @{text m}
+  in initial position, but unlike @{command "proof"} it retains
+  ``@{text "proof(prove)"}'' mode.  Thus consecutive method
+  applications may be given just as in tactic scripts.
+  
+  Facts are passed to @{text m} as indicated by the goal's
+  forward-chain mode, and are \emph{consumed} afterwards.  Thus any
+  further @{command "apply"} command would always work in a purely
+  backward manner.
+  
+  \item [@{command "apply_end"}~@{text "m"}] applies proof method
+  @{text m} as if in terminal position.  Basically, this simulates a
+  multi-step tactic script for @{command "qed"}, but may be given
+  anywhere within the proof body.
+  
+  No facts are passed to @{method m} here.  Furthermore, the static
+  context is that of the enclosing goal (as for actual @{command
+  "qed"}).  Thus the proof method may not refer to any assumptions
+  introduced in the current body, for example.
+  
+  \item [@{command "done"}] completes a proof script, provided that
+  the current goal state is solved completely.  Note that actual
+  structured proof commands (e.g.\ ``@{command "."}'' or @{command
+  "sorry"}) may be used to conclude proof scripts as well.
+
+  \item [@{command "defer"}~@{text n} and @{command "prefer"}~@{text
+  n}] shuffle the list of pending goals: @{command "defer"} puts off
+  sub-goal @{text n} to the end of the list (@{text "n = 1"} by
+  default), while @{command "prefer"} brings sub-goal @{text n} to the
+  front.
+  
+  \item [@{command "back"}] does back-tracking over the result
+  sequence of the latest proof command.  Basically, any proof command
+  may return multiple results.
+  
+  \end{descr}
+
+  Any proper Isar proof method may be used with tactic script commands
+  such as @{command "apply"}.  A few additional emulations of actual
+  tactics are provided as well; these would be never used in actual
+  structured proofs, of course.
+*}
+
+
+subsection {* Meta-linguistic features *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "oops"} & : & \isartrans{proof}{theory} \\
+  \end{matharray}
+
+  The @{command "oops"} command discontinues the current proof
+  attempt, while considering the partial proof text as properly
+  processed.  This is conceptually quite different from ``faking''
+  actual proofs via @{command_ref "sorry"} (see
+  \secref{sec:proof-steps}): @{command "oops"} does not observe the
+  proof structure at all, but goes back right to the theory level.
+  Furthermore, @{command "oops"} does not produce any result theorem
+  --- there is no intended claim to be able to complete the proof
+  anyhow.
+
+  A typical application of @{command "oops"} is to explain Isar proofs
+  \emph{within} the system itself, in conjunction with the document
+  preparation tools of Isabelle described in \cite{isabelle-sys}.
+  Thus partial or even wrong proof attempts can be discussed in a
+  logically sound manner.  Note that the Isabelle {\LaTeX} macros can
+  be easily adapted to print something like ``@{text "\<dots>"}'' instead of
+  the keyword ``@{command "oops"}''.
+
+  \medskip The @{command "oops"} command is undo-able, unlike
+  @{command_ref "kill"} (see \secref{sec:history}).  The effect is to
+  get back to the theory just before the opening of the proof.
+*}
+
+
+section {* Other commands *}
+
+subsection {* Diagnostics *}
+
+text {*
+  \begin{matharray}{rcl}
+    \isarcmd{pr}^* & : & \isarkeep{\cdot} \\
+    \isarcmd{thm}^* & : & \isarkeep{theory~|~proof} \\
+    \isarcmd{term}^* & : & \isarkeep{theory~|~proof} \\
+    \isarcmd{prop}^* & : & \isarkeep{theory~|~proof} \\
+    \isarcmd{typ}^* & : & \isarkeep{theory~|~proof} \\
+    \isarcmd{prf}^* & : & \isarkeep{theory~|~proof} \\
+    \isarcmd{full_prf}^* & : & \isarkeep{theory~|~proof} \\
+  \end{matharray}
+
+  These diagnostic commands assist interactive development.  Note that
+  @{command undo} does not apply here, the theory or proof
+  configuration is not changed.
+
+  \begin{rail}
+    'pr' modes? nat? (',' nat)?
+    ;
+    'thm' modes? thmrefs
+    ;
+    'term' modes? term
+    ;
+    'prop' modes? prop
+    ;
+    'typ' modes? type
+    ;
+    'prf' modes? thmrefs?
+    ;
+    'full\_prf' modes? thmrefs?
+    ;
+
+    modes: '(' (name + ) ')'
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "pr"}~@{text "goals, prems"}] prints the current
+  proof state (if present), including the proof context, current facts
+  and goals.  The optional limit arguments affect the number of goals
+  and premises to be displayed, which is initially 10 for both.
+  Omitting limit values leaves the current setting unchanged.
+
+  \item [@{command "thm"}~@{text "a\<^sub>1 \<dots> a\<^sub>n"}] retrieves
+  theorems from the current theory or proof context.  Note that any
+  attributes included in the theorem specifications are applied to a
+  temporary context derived from the current theory or proof; the
+  result is discarded, i.e.\ attributes involved in @{text "a\<^sub>1,
+  \<dots>, a\<^sub>n"} do not have any permanent effect.
+
+  \item [@{command "term"}~@{text t} and @{command "prop"}~@{text \<phi>}]
+  read, type-check and print terms or propositions according to the
+  current theory or proof context; the inferred type of @{text t} is
+  output as well.  Note that these commands are also useful in
+  inspecting the current environment of term abbreviations.
+
+  \item [@{command "typ"}~@{text \<tau>}] reads and prints types of the
+  meta-logic according to the current theory or proof context.
+
+  \item [@{command "prf"}] displays the (compact) proof term of the
+  current proof state (if present), or of the given theorems. Note
+  that this requires proof terms to be switched on for the current
+  object logic (see the ``Proof terms'' section of the Isabelle
+  reference manual for information on how to do this).
+
+  \item [@{command "full_prf"}] is like @{command "prf"}, but displays
+  the full proof term, i.e.\ also displays information omitted in the
+  compact proof term, which is denoted by ``@{verbatim _}''
+  placeholders there.
+
+  \end{descr}
+
+  All of the diagnostic commands above admit a list of @{text modes}
+  to be specified, which is appended to the current print mode (see
+  also \cite{isabelle-ref}).  Thus the output behavior may be modified
+  according particular print mode features.  For example, @{command
+  "pr"}~@{text "(latex xsymbols symbols)"} would print the current
+  proof state with mathematical symbols and special characters
+  represented in {\LaTeX} source, according to the Isabelle style
+  \cite{isabelle-sys}.
+
+  Note that antiquotations (cf.\ \secref{sec:antiq}) provide a more
+  systematic way to include formal items into the printed text
+  document.
+*}
+
+
+subsection {* Inspecting the context *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "print_commands"}^* & : & \isarkeep{\cdot} \\
+    @{command_def "print_theory"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "print_syntax"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "print_methods"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "print_attributes"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "print_theorems"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "find_theorems"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "thms_deps"}^* & : & \isarkeep{theory~|~proof} \\
+    @{command_def "print_facts"}^* & : & \isarkeep{proof} \\
+    @{command_def "print_binds"}^* & : & \isarkeep{proof} \\
+  \end{matharray}
+
+  \begin{rail}
+    'print\_theory' ( '!'?)
+    ;
+
+    'find\_theorems' (('(' (nat)? ('with\_dups')? ')')?) (criterion *)
+    ;
+    criterion: ('-'?) ('name' ':' nameref | 'intro' | 'elim' | 'dest' |
+      'simp' ':' term | term)
+    ;
+    'thm\_deps' thmrefs
+    ;
+  \end{rail}
+
+  These commands print certain parts of the theory and proof context.
+  Note that there are some further ones available, such as for the set
+  of rules declared for simplifications.
+
+  \begin{descr}
+  
+  \item [@{command "print_commands"}] prints Isabelle's outer theory
+  syntax, including keywords and command.
+  
+  \item [@{command "print_theory"}] prints the main logical content of
+  the theory context; the ``@{text "!"}'' option indicates extra
+  verbosity.
+
+  \item [@{command "print_syntax"}] prints the inner syntax of types
+  and terms, depending on the current context.  The output can be very
+  verbose, including grammar tables and syntax translation rules.  See
+  \cite[\S7, \S8]{isabelle-ref} for further information on Isabelle's
+  inner syntax.
+  
+  \item [@{command "print_methods"}] prints all proof methods
+  available in the current theory context.
+  
+  \item [@{command "print_attributes"}] prints all attributes
+  available in the current theory context.
+  
+  \item [@{command "print_theorems"}] prints theorems resulting from
+  the last command.
+  
+  \item [@{command "find_theorems"}~@{text criteria}] retrieves facts
+  from the theory or proof context matching all of given search
+  criteria.  The criterion @{text "name: p"} selects all theorems
+  whose fully qualified name matches pattern @{text p}, which may
+  contain ``@{text "*"}'' wildcards.  The criteria @{text intro},
+  @{text elim}, and @{text dest} select theorems that match the
+  current goal as introduction, elimination or destruction rules,
+  respectively.  The criterion @{text "simp: t"} selects all rewrite
+  rules whose left-hand side matches the given term.  The criterion
+  term @{text t} selects all theorems that contain the pattern @{text
+  t} -- as usual, patterns may contain occurrences of the dummy
+  ``@{verbatim _}'', schematic variables, and type constraints.
+  
+  Criteria can be preceded by ``@{text "-"}'' to select theorems that
+  do \emph{not} match. Note that giving the empty list of criteria
+  yields \emph{all} currently known facts.  An optional limit for the
+  number of printed facts may be given; the default is 40.  By
+  default, duplicates are removed from the search result. Use
+  @{keyword "with_dups"} to display duplicates.
+  
+  \item [@{command "thm_deps"}~@{text "a\<^sub>1 \<dots> a\<^sub>n"}]
+  visualizes dependencies of facts, using Isabelle's graph browser
+  tool (see also \cite{isabelle-sys}).
+  
+  \item [@{command "print_facts"}] prints all local facts of the
+  current context, both named and unnamed ones.
+  
+  \item [@{command "print_binds"}] prints all term abbreviations
+  present in the context.
+
+  \end{descr}
+*}
+
+
+subsection {* History commands \label{sec:history} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "undo"}^{{ * }{ * }} & : & \isarkeep{\cdot} \\
+    @{command_def "redo"}^{{ * }{ * }} & : & \isarkeep{\cdot} \\
+    @{command_def "kill"}^{{ * }{ * }} & : & \isarkeep{\cdot} \\
+  \end{matharray}
+
+  The Isabelle/Isar top-level maintains a two-stage history, for
+  theory and proof state transformation.  Basically, any command can
+  be undone using @{command "undo"}, excluding mere diagnostic
+  elements.  Its effect may be revoked via @{command "redo"}, unless
+  the corresponding @{command "undo"} step has crossed the beginning
+  of a proof or theory.  The @{command "kill"} command aborts the
+  current history node altogether, discontinuing a proof or even the
+  whole theory.  This operation is \emph{not} undo-able.
+
+  \begin{warn}
+    History commands should never be used with user interfaces such as
+    Proof~General \cite{proofgeneral,Aspinall:TACAS:2000}, which takes
+    care of stepping forth and back itself.  Interfering by manual
+    @{command "undo"}, @{command "redo"}, or even @{command "kill"}
+    commands would quickly result in utter confusion.
+  \end{warn}
+*}
+
+
+subsection {* System operations *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{command_def "cd"}^* & : & \isarkeep{\cdot} \\
+    @{command_def "pwd"}^* & : & \isarkeep{\cdot} \\
+    @{command_def "use_thy"}^* & : & \isarkeep{\cdot} \\
+    @{command_def "display_drafts"}^* & : & \isarkeep{\cdot} \\
+    @{command_def "print_drafts"}^* & : & \isarkeep{\cdot} \\
+  \end{matharray}
+
+  \begin{rail}
+    ('cd' | 'use\_thy' | 'update\_thy') name
+    ;
+    ('display\_drafts' | 'print\_drafts') (name +)
+    ;
+  \end{rail}
+
+  \begin{descr}
+
+  \item [@{command "cd"}~@{text path}] changes the current directory
+  of the Isabelle process.
+
+  \item [@{command "pwd"}] prints the current working directory.
+
+  \item [@{command "use_thy"}~@{text A}] preload theory @{text A}.
+  These system commands are scarcely used when working interactively,
+  since loading of theories is done automatically as required.
+
+  \item [@{command "display_drafts"}~@{text paths} and @{command
+  "print_drafts"}~@{text paths}] perform simple output of a given list
+  of raw source files.  Only those symbols that do not require
+  additional {\LaTeX} packages are displayed properly, everything else
+  is left verbatim.
+
+  \end{descr}
+*}
+
+end




