updated
authorChristian Urban <urbanc@in.tum.de>
Fri, 18 Aug 2017 14:51:29 +0100
changeset 268 6746f5e1f1f8
parent 267 32b222d77fa0
child 269 12772d537b71
updated
thys/Exercises.thy
thys/Journal/Paper.thy
thys/Journal/document/root.bib
thys/Journal/document/root.tex
thys/Lexer.thy
thys/Positions.thy
thys/Spec.thy
--- a/thys/Exercises.thy	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Exercises.thy	Fri Aug 18 14:51:29 2017 +0100
@@ -49,7 +49,8 @@
 using Nil_is_append_conv apply blast
 apply blast
 apply(auto)
-using Star_string by fastforce
+using Star_cstring
+by (metis concat_eq_Nil_conv) 
 
 
 lemma atmostempty_correctness_aux:
@@ -78,7 +79,7 @@
   assumes "A \<subseteq> {[]}"
   shows "A\<star> \<subseteq> {[]}"
 using assms
-using Star_string concat_eq_Nil_conv empty_iff insert_iff subsetI subset_singletonD by fastforce
+using Star_cstring concat_eq_Nil_conv empty_iff insert_iff subsetI subset_singletonD by fastforce
 
 lemma Star_empty_string_finite:
   shows "finite ({[]}\<star>)"
--- a/thys/Journal/Paper.thy	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Journal/Paper.thy	Fri Aug 18 14:51:29 2017 +0100
@@ -63,7 +63,6 @@
   set ("_" [73] 73) and
  
   Prf ("_ : _" [75,75] 75) and
-  CPrf ("_ \<^raw:\mbox{\textbf{\textlengthmark}}> _" [75,75] 75) and
   Posix ("'(_, _') \<rightarrow> _" [63,75,75] 75) and
  
   lexer ("lexer _ _" [78,78] 77) and 
@@ -83,20 +82,18 @@
   PosOrd_ex ("_ \<prec> _" [77,77] 77) and
   PosOrd_ex_eq ("_ \<^raw:\mbox{$\preccurlyeq$}> _" [77,77] 77) and
   pflat_len ("\<parallel>_\<parallel>\<^bsub>_\<^esub>") and
-  nprec ("_ \<^raw:\mbox{$\not\prec$}> _" [77,77] 77) 
+  nprec ("_ \<^raw:\mbox{$\not\prec$}> _" [77,77] 77) and
 
-  (*
-  ValOrd ("_ >\<^bsub>_\<^esub> _" [77,77,77] 77) and
-  ValOrdEq ("_ \<ge>\<^bsub>_\<^esub> _" [77,77,77] 77)
-  *)
+  DUMMY ("\<^raw:\underline{\hspace{2mm}}>")
+
 
 definition 
   "match r s \<equiv> nullable (ders s r)"
 
 
-lemma CV_STAR_ONE_empty: 
-  shows "CV (STAR ONE) [] = {Stars []}"
-by(auto simp add: CV_def elim: CPrf.cases intro: CPrf.intros)
+lemma LV_STAR_ONE_empty: 
+  shows "LV (STAR ONE) [] = {Stars []}"
+by(auto simp add: LV_def elim: Prf.cases intro: Prf.intros)
 
 
 
@@ -139,7 +136,7 @@
 one way of how the string is matched. There are two commonly used
 disambiguation strategies to generate a unique answer: one is called GREEDY
 matching \cite{Frisch2004} and the other is POSIX
-matching~\cite{POSIX,Kuklewicz,OkuiSuzuki2013,Sulzmann2014,Vansummeren2006}. For example consider
+matching~\cite{POSIX,Kuklewicz,OkuiSuzuki2010,Sulzmann2014,Vansummeren2006}. For example consider
 the string @{term xy} and the regular expression \mbox{@{term "STAR (ALT
 (ALT x y) xy)"}}. Either the string can be matched in two `iterations' by
 the single letter-regular expressions @{term x} and @{term y}, or directly
@@ -149,14 +146,15 @@
 instant gratification to delayed repletion). The second case is POSIX
 matching, which prefers the longest match.
 
-In the context of lexing, where an input string needs to be split up into a
-sequence of tokens, POSIX is the more natural disambiguation strategy for
-what programmers consider basic syntactic building blocks in their programs.
-These building blocks are often specified by some regular expressions, say
-@{text "r\<^bsub>key\<^esub>"} and @{text "r\<^bsub>id\<^esub>"} for recognising keywords and
-identifiers, respectively. There are a few underlying (informal) rules behind
-tokenising a string in a POSIX \cite{POSIX} fashion according to a collection of regular
-expressions:
+In the context of lexing, where an input string needs to be split up
+into a sequence of tokens, POSIX is the more natural disambiguation
+strategy for what programmers consider basic syntactic building blocks
+in their programs.  These building blocks are often specified by some
+regular expressions, say @{text "r\<^bsub>key\<^esub>"} and @{text
+"r\<^bsub>id\<^esub>"} for recognising keywords and identifiers,
+respectively. There are a few underlying (informal) rules behind
+tokenising a string in a POSIX \cite{POSIX} fashion according to a
+collection of regular expressions:
 
 \begin{itemize} 
 \item[$\bullet$] \emph{The Longest Match Rule} (or \emph{``{M}aximal {M}unch {R}ule''}):
@@ -171,20 +169,28 @@
 not match an empty string unless this is the only match for the repetition.\smallskip
 
 \item[$\bullet$] \emph{Empty String Rule:} An empty string shall be considered to 
-be longer than no match at all.\marginpar{Explain its purpose}
+be longer than no match at all.
 \end{itemize}
 
-\noindent Consider for example a regular expression @{text "r\<^bsub>key\<^esub>"} for recognising keywords
-such as @{text "if"}, @{text "then"} and so on; and @{text "r\<^bsub>id\<^esub>"}
+\noindent Consider for example a regular expression @{text
+"r\<^bsub>key\<^esub>"} for recognising keywords such as @{text "if"},
+@{text "then"} and so on; and @{text "r\<^bsub>id\<^esub>"}
 recognising identifiers (say, a single character followed by
 characters or numbers).  Then we can form the regular expression
-@{text "(r\<^bsub>key\<^esub> + r\<^bsub>id\<^esub>)\<^sup>\<star>"} and use POSIX matching to tokenise strings,
-say @{text "iffoo"} and @{text "if"}.  For @{text "iffoo"} we obtain
-by the Longest Match Rule a single identifier token, not a keyword
-followed by an identifier. For @{text "if"} we obtain by the Priority
-Rule a keyword token, not an identifier token---even if @{text "r\<^bsub>id\<^esub>"}
-matches also. By the Star Rule we know @{text "(r\<^bsub>key\<^esub> + r\<^bsub>id\<^esub>)\<^sup>\<star>"} matches @{text "iffoo"}, respectively @{text "if"}, in exactly one
-`iteration' of the star.
+@{text "(r\<^bsub>key\<^esub> + r\<^bsub>id\<^esub>)\<^sup>\<star>"}
+and use POSIX matching to tokenise strings, say @{text "iffoo"} and
+@{text "if"}.  For @{text "iffoo"} we obtain by the Longest Match Rule
+a single identifier token, not a keyword followed by an
+identifier. For @{text "if"} we obtain by the Priority Rule a keyword
+token, not an identifier token---even if @{text "r\<^bsub>id\<^esub>"}
+matches also. By the Star Rule we know @{text "(r\<^bsub>key\<^esub> +
+r\<^bsub>id\<^esub>)\<^sup>\<star>"} matches @{text "iffoo"},
+respectively @{text "if"}, in exactly one `iteration' of the star. The
+Empty String Rule is for cases where @{text
+"(a\<^sup>\<star>)\<^sup>\<star>"}, for example, matches against the
+string @{text "bc"}. Then the longest initial matched substring is the
+empty string, which is matched by both the whole regular expression
+and the parenthesised sub-expression.
 
 
 One limitation of Brzozowski's matcher is that it only generates a
@@ -205,11 +211,10 @@
 algorithm. This proof idea is inspired by work of Frisch and Cardelli
 \cite{Frisch2004} on a GREEDY regular expression matching
 algorithm. However, we were not able to establish transitivity and
-totality for the ``order relation'' by Sulzmann and Lu. \marginpar{We probably drop this section} 
-??In Section
-\ref{argu} we identify some inherent problems with their approach (of
+totality for the ``order relation'' by Sulzmann and Lu. 
+There are some inherent problems with their approach (of
 which some of the proofs are not published in \cite{Sulzmann2014});
-perhaps more importantly, we give a simple inductive (and
+perhaps more importantly, we give in this paper a simple inductive (and
 algorithm-independent) definition of what we call being a {\em POSIX
 value} for a regular expression @{term r} and a string @{term s}; we
 show that the algorithm computes such a value and that such a value is
@@ -252,7 +257,7 @@
 Our specification of a POSIX value consists of a simple inductive definition
 that given a string and a regular expression uniquely determines this value.
 We also show that our definition is equivalent to an ordering 
-of values based on positions by Okui and Suzuki \cite{OkuiSuzuki2013}.
+of values based on positions by Okui and Suzuki \cite{OkuiSuzuki2010}.
 Derivatives as calculated by Brzozowski's method are usually more complex
 regular expressions than the initial one; various optimisations are
 possible. We prove the correctness when simplifications of @{term "ALT ZERO
@@ -402,9 +407,10 @@
 
 text {* 
 
-  The clever idea by Sulzmann and Lu \cite{Sulzmann2014} is to use
-  values for encoding \emph{how} a regular expression matches a string
-  and then define a function on values that mirrors (but inverts) the
+  There have been many previous works that use values for encoding 
+  \emph{how} a regular expression matches a string.
+  The clever idea by Sulzmann and Lu \cite{Sulzmann2014} is to 
+  define a function on values that mirrors (but inverts) the
   construction of the derivative on regular expressions. \emph{Values}
   are defined as the inductive datatype
 
@@ -440,98 +446,89 @@
   \end{center}
 
   \noindent Sulzmann and Lu also define inductively an inhabitation relation
-  that associates values to regular expressions
+  that associates values to regular expressions. We define this relation as 
+  follows:\footnote{Note that the rule for @{term Stars} differs from our 
+  erlier paper \cite{AusafDyckhoffUrban2016}. There we used the original
+  definition by Sulzmann and Lu which does not require that the values @{term "v \<in> set vs"}
+  flatten to a non-empty string. The reason for introducing the 
+  more restricted version of lexical values is convenience later 
+  on when reasoning about 
+  an ordering relation for values.} 
 
   \begin{center}
-  \begin{tabular}{c}
+  \begin{tabular}{c@ {\hspace{12mm}}c}
   \\[-8mm]
-  @{thm[mode=Axiom] Prf.intros(4)} \qquad
+  @{thm[mode=Axiom] Prf.intros(4)} & 
   @{thm[mode=Axiom] Prf.intros(5)[of "c"]}\\[4mm]
-  @{thm[mode=Rule] Prf.intros(2)[of "v\<^sub>1" "r\<^sub>1" "r\<^sub>2"]} \qquad 
+  @{thm[mode=Rule] Prf.intros(2)[of "v\<^sub>1" "r\<^sub>1" "r\<^sub>2"]} &
   @{thm[mode=Rule] Prf.intros(3)[of "v\<^sub>2" "r\<^sub>1" "r\<^sub>2"]}\\[4mm]
-  @{thm[mode=Rule] Prf.intros(1)[of "v\<^sub>1" "r\<^sub>1" "v\<^sub>2" "r\<^sub>2"]} \qquad
+  @{thm[mode=Rule] Prf.intros(1)[of "v\<^sub>1" "r\<^sub>1" "v\<^sub>2" "r\<^sub>2"]}  &
   @{thm[mode=Rule] Prf.intros(6)[of "vs"]}
   \end{tabular}
   \end{center}
 
-  \noindent 
-  where in the clause for @{const "Stars"} we use the notation @{term "v \<in> set vs"}
-  for indicating that @{text v} is a member in the list @{text vs}.
-  Note that no values are associated with the regular expression
-  @{term ZERO}, and that the only value associated with the regular
-  expression @{term ONE} is @{term Void}, pronounced (if one must) as @{text
-  "Void"}. It is routine to establish how values ``inhabiting'' a regular
-  expression correspond to the language of a regular expression, namely
+  \noindent where in the clause for @{const "Stars"} we use the
+  notation @{term "v \<in> set vs"} for indicating that @{text v} is a
+  member in the list @{text vs}.  We require in this rule that every
+  value in @{term vs} flattens to a non-empty string. The idea is that
+  @{term "Stars"}-values satisfy the informal Star Rule (see Introduction)
+  where the $^\star$ does not match the empty string unless this is
+  the only match for the repetition.  Note also that no values are
+  associated with the regular expression @{term ZERO}, and that the
+  only value associated with the regular expression @{term ONE} is
+  @{term Void}.  It is routine to establish how values ``inhabiting''
+  a regular expression correspond to the language of a regular
+  expression, namely
 
   \begin{proposition}
   @{thm L_flat_Prf}
   \end{proposition}
 
   \noindent
-  Given a regular expression @{text r} and a string @{text s}, we can define the 
+  Given a regular expression @{text r} and a string @{text s}, we define the 
   set of all \emph{Lexical Values} inhabited by @{text r} with the underlying string 
-  being @{text s} by
+  being @{text s}:\footnote{Okui and Suzuki refer to our lexical values 
+  as \emph{canonical values} in \cite{OkuiSuzuki2010}. The notion of \emph{non-problematic
+  values} by Cardelli and Frisch \cite{Frisch2004} is similar, but not identical
+  to our lexical values.}
   
   \begin{center}
   @{thm LV_def}
   \end{center}
 
-  \noindent However, later on it will sometimes be necessary to
-  restrict the set of lexical values to a subset called
-  \emph{Canonical Values}. The idea of canonical values is that they
-  satisfy the Star Rule (see Introduction) where the $^\star$ does not
-  match the empty string unless this is the only match for the
-  repetition.  One way to define canonical values formally is to use a
-  stronger inhabitation relation, written @{term "\<Turnstile> DUMMY : DUMMY"}, which has the same rules as @{term
-  "\<turnstile> DUMMY : DUMMY"} shown above, except that the rule for 
-  @{term Stars} has
-  the additional side-condition of flattened values not being the
-  empty string, namely
+  \noindent The main property of @{term "LV r s"} is that it is alway finite.
+
+  \begin{proposition}
+  @{thm LV_finite}
+  \end{proposition}
 
-  \begin{center}
-  @{thm [mode=Rule] CPrf.intros(6)}
-  \end{center}
-
-  \noindent
-  With this we can define
-  
-  \begin{center}
-  @{thm CV_def}
-  \end{center}
-
-  \noindent
-  Clearly we have @{thm LV_CV_subset}.
-  The main point of canonical values is that for every regular expression @{text r} and every
-  string @{text s}, the set @{term "CV r s"} is finite.
+  \noindent This finiteness property does not hold in general if we
+  remove the side-condition about @{term "flat v \<noteq> []"} in the
+  @{term Stars}-rule above. For example using Sulzmann and Lu's
+  less restrictive definition, @{term "LV (STAR ONE) []"} would contain
+  infinitely many values, but according to our more restricted
+  definition @{thm LV_STAR_ONE_empty}.
 
-  \begin{lemma}
-  @{thm CV_finite}
-  \end{lemma}
-
-  \noindent This finiteness property does not generally hold for lexical values where
-  for example @{term "LV (STAR ONE) []"} contains infinitely many
-  values, but @{thm CV_STAR_ONE_empty}. However, if a regular
-  expression @{text r} matches a string @{text s}, then in general the
-  set @{term "CV r s"} is not just a
-  singleton set.  In case of POSIX matching the problem is to
-  calculate the unique value that satisfies the (informal) POSIX rules
-  from the Introduction. It will turn out that this POSIX value is in fact a
-  canonical value.
-
-  Graphically the POSIX value calculation algorithm by
-  Sulzmann and Lu can be illustrated by the picture in Figure~\ref{Sulz}
-  where the path from the left to the right involving @{term derivatives}/@{const
-  nullable} is the first phase of the algorithm (calculating successive
-  \Brz's derivatives) and @{const mkeps}/@{text inj}, the path from right to
-  left, the second phase. This picture shows the steps required when a
-  regular expression, say @{text "r\<^sub>1"}, matches the string @{term
-  "[a,b,c]"}. We first build the three derivatives (according to @{term a},
-  @{term b} and @{term c}). We then use @{const nullable} to find out
-  whether the resulting derivative regular expression @{term "r\<^sub>4"}
-  can match the empty string. If yes, we call the function @{const mkeps}
-  that produces a value @{term "v\<^sub>4"} for how @{term "r\<^sub>4"} can
-  match the empty string (taking into account the POSIX constraints in case
-  there are several ways). This function is defined by the clauses:
+  If a regular expression @{text r} matches a string @{text s}, then
+  generally the set @{term "LV r s"} is not just a singleton set.  In
+  case of POSIX matching the problem is to calculate the unique lexical value
+  that satisfies the (informal) POSIX rules from the Introduction.
+  Graphically the POSIX value calculation algorithm by Sulzmann and Lu
+  can be illustrated by the picture in Figure~\ref{Sulz} where the
+  path from the left to the right involving @{term
+  derivatives}/@{const nullable} is the first phase of the algorithm
+  (calculating successive \Brz's derivatives) and @{const
+  mkeps}/@{text inj}, the path from right to left, the second
+  phase. This picture shows the steps required when a regular
+  expression, say @{text "r\<^sub>1"}, matches the string @{term
+  "[a,b,c]"}. We first build the three derivatives (according to
+  @{term a}, @{term b} and @{term c}). We then use @{const nullable}
+  to find out whether the resulting derivative regular expression
+  @{term "r\<^sub>4"} can match the empty string. If yes, we call the
+  function @{const mkeps} that produces a value @{term "v\<^sub>4"}
+  for how @{term "r\<^sub>4"} can match the empty string (taking into
+  account the POSIX constraints in case there are several ways). This
+  function is defined by the clauses:
 
 \begin{figure}[t]
 \begin{center}
@@ -794,15 +791,15 @@
   that in each ``iteration'' of the star, some non-empty substring needs to
   be ``chipped'' away; only in case of the empty string we accept @{term
   "Stars []"} as the POSIX value. Indeed we can show that our POSIX value
-  is a canonical value which excludes those @{text Stars} containing values 
+  is a lexical value which excludes those @{text Stars} containing values 
   that flatten to the empty string.
 
   \begin{lemma}
-  @{thm [mode=IfThen] Posix_CV}
+  @{thm [mode=IfThen] Posix_LV}
   \end{lemma}
 
   \begin{proof}
-  By routine induction on @{thm (prem 1) Posix_CV}.\qed 
+  By routine induction on @{thm (prem 1) Posix_LV}.\qed 
   \end{proof}
 
   \noindent
@@ -922,6 +919,270 @@
 
 *}
 
+section {* Ordering of Values according to Okui and Suzuki*}
+
+text {*
+  
+  While in the previous section we have defined POSIX values directly
+  in terms of a ternary relation (see inference rules in Figure~\ref{POSIXrules}),
+  Sulzmann and Lu took a different approach in \cite{Sulzmann2014}:
+  they introduced an ordering for values and identified POSIX values
+  as the maximal elements.  An extended version of \cite{Sulzmann2014}
+  is available at the website of its first author; this includes more
+  details of their proofs, but which are evidently not in final form
+  yet. Unfortunately, we were not able to verify claims that their
+  ordering has properties such as being transitive or having maximal
+  elements.
+ 
+  Okui and Suzuki \cite{OkuiSuzuki2010,OkuiSuzukiTech} described
+   another ordering of values, which they use to establish the correctness of
+   their automata-based algorithm for POSIX matching.  Their ordering
+   resembles some aspects of the one given by Sulzmann and Lu, but
+   is quite different. To begin with, Okui and Suzuki identify POSIX
+   values as least elements in their ordering. A more substantial 
+    difference is that the ordering by Okui
+   and Suzuki uses \emph{positions} in order to identify and
+   compare subvalues, whereby positions are lists of natural
+   numbers. This allows them to quite naturally formalise the Longest
+   Match and Priority rules of the informal POSIX standard.  Consider
+   for example the value @{term v} of the form @{term "Stars [Seq
+   (Char x) (Char y), Char z]"}, say.  At position @{text "[0,1]"} of
+   this value is the subvalue @{text "Char y"} and at position @{text
+   "[1]"} the subvalue @{term "Char z"}.  At the `root' position, or
+   empty list @{term "[]"}, is the whole value @{term v}. The
+   positions @{text "[0,1,0]"} and @{text "[2]"}, for example, are
+   outside of @{text v}. If it exists, the subvalue of @{term v} at a
+   position @{text p}, written @{term "at v p"}, can be recursively
+   defined by
+  
+  \begin{center}
+  \begin{tabular}{r@ {\hspace{0mm}}lcl}
+  @{term v} &  @{text "\<downharpoonleft>\<^bsub>[]\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(1)}\\
+  @{term "Left v"} & @{text "\<downharpoonleft>\<^bsub>0::ps\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(2)}\\
+  @{term "Right v"} & @{text "\<downharpoonleft>\<^bsub>1::ps\<^esub>"} & @{text "\<equiv>"} & 
+  @{thm (rhs) at.simps(3)[simplified Suc_0_fold]}\\
+  @{term "Seq v\<^sub>1 v\<^sub>2"} & @{text "\<downharpoonleft>\<^bsub>0::ps\<^esub>"} & @{text "\<equiv>"} & 
+  @{thm (rhs) at.simps(4)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} \\
+  @{term "Seq v\<^sub>1 v\<^sub>2"} & @{text "\<downharpoonleft>\<^bsub>1::ps\<^esub>"}
+  & @{text "\<equiv>"} & 
+  @{thm (rhs) at.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2", simplified Suc_0_fold]} \\
+  @{term "Stars vs"} & @{text "\<downharpoonleft>\<^bsub>n::ps\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(6)}\\
+  \end{tabular} 
+  \end{center}
+
+  \noindent We use Isabelle's notation @{term "vs ! n"} for the
+  @{text n}th element in a list.  The set of positions inside a value @{text v},
+  written @{term "Pos v"}, is given by the clauses
+
+  \begin{center}
+  \begin{tabular}{lcl}
+  @{thm (lhs) Pos.simps(1)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(1)}\\
+  @{thm (lhs) Pos.simps(2)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(2)}\\
+  @{thm (lhs) Pos.simps(3)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(3)}\\
+  @{thm (lhs) Pos.simps(4)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(4)}\\
+  @{thm (lhs) Pos.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
+  & @{text "\<equiv>"} 
+  & @{thm (rhs) Pos.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}\\
+  @{thm (lhs) Pos_stars} & @{text "\<equiv>"} & @{thm (rhs) Pos_stars}\\
+  \end{tabular}
+  \end{center}
+
+  \noindent 
+  In the last clause @{text len} stands for the length of a list. Clearly
+  for every position inside a value there exists a subvalue at that position.
+ 
+
+  To help understanding the ordering of Okui and Suzuki, consider again 
+  the earlier value
+  @{text v} and compare it with the following @{text w}:
+
+  \begin{center}
+  \begin{tabular}{l}
+  @{term "v == Stars [Seq (Char x) (Char y), Char z]"}\\
+  @{term "w == Stars [Char x, Char y, Char z]"}  
+  \end{tabular}
+  \end{center}
+
+  \noindent Both values match the string @{text "xyz"}, that means if
+  we flatten the values at their respective root position, we obtain
+  @{text "xyz"}. However, at position @{text "[0]"}, @{text v} matches
+  @{text xy} whereas @{text w} matches only the shorter @{text x}. So
+  according to the Longest Match Rule, we should prefer @{text v},
+  rather than @{text w} as POSIX value for string @{text xyz} (and
+  corresponding regular expression). In order to
+  formalise this idea, Okui and Suzuki introduce a measure for
+  subvalues at position @{text p}, called the \emph{norm} of @{text v}
+  at position @{text p}. We can define this measure in Isabelle as an
+  integer as follows
+  
+  \begin{center}
+  @{thm pflat_len_def}
+  \end{center}
+
+  \noindent where we take the length of the flattened value at
+  position @{text p}, provided the position is inside @{text v}; if
+  not, then the norm is @{text "-1"}. The default is crucial
+  for the POSIX requirement of preferring a @{text Left}-value
+  over a @{text Right}-value (if they can match the same string---see
+  the Priority Rule from the Introduction). For this consider
+
+  \begin{center}
+  @{term "v == Left (Char x)"} \qquad and \qquad @{term "w == Right (Char x)"}
+  \end{center}
+
+  \noindent Both values match @{text x}, but at position @{text "[0]"}
+  the norm of @{term v} is @{text 1} (the subvalue matches @{text x}), but the
+  norm of @{text w} is @{text "-1"} (the position is outside @{text w}
+  according to how we defined the `inside' positions of @{text Left}-
+  and @{text Right}-values).  Of course at position @{text "[1]"}, the
+  norms @{term "pflat_len v [1]"} and @{term "pflat_len w [1]"} are
+  reversed, but the point is that subvalues will be analysed according to
+  lexicographically orderd positions.  This order, written @{term
+  "DUMMY \<sqsubset>lex DUMMY"}, can be conveniently formalised by
+  three inference rules
+
+  \begin{center}
+  \begin{tabular}{ccc}
+  @{thm [mode=Axiom] lex_list.intros(1)}\hspace{1cm} &
+  @{thm [mode=Rule] lex_list.intros(3)[where ?p1.0="p\<^sub>1" and ?p2.0="p\<^sub>2" and
+                                            ?ps1.0="ps\<^sub>1" and ?ps2.0="ps\<^sub>2"]}\hspace{1cm} &
+  @{thm [mode=Rule] lex_list.intros(2)[where ?ps1.0="ps\<^sub>1" and ?ps2.0="ps\<^sub>2"]}
+  \end{tabular}
+  \end{center}
+
+  With the norm and lexicographic order of positions in place,
+  we can state the key definition of Okui and Suzuki
+  \cite{OkuiSuzuki2010}: a value @{term "v\<^sub>1"} is \emph{smaller} than
+  @{term "v\<^sub>2"} if and only if  $(i)$ the norm at position @{text p} is
+  greater in @{term "v\<^sub>1"} (that is the string @{term "flat (at v\<^sub>1 p)"} is longer 
+  than @{term "flat (at v\<^sub>2 p)"}) and $(ii)$ all subvalues at 
+  positions that are inside @{term "v\<^sub>1"} or @{term "v\<^sub>2"} and that are
+  lexicographically smaller than @{text p}, we have the same norm, namely
+
+ \begin{center}
+ \begin{tabular}{c}
+ @{thm (lhs) PosOrd_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} 
+ @{text "\<equiv>"} 
+ $\begin{cases}
+ (i) & @{term "pflat_len v\<^sub>1 p > pflat_len v\<^sub>2 p"}   \quad\text{and}\smallskip \\
+ (ii) & @{term "(\<forall>q \<in> Pos v\<^sub>1 \<union> Pos v\<^sub>2. q \<sqsubset>lex p --> pflat_len v\<^sub>1 q = pflat_len v\<^sub>2 q)"}
+ \end{cases}$
+ \end{tabular}
+ \end{center}
+
+ \noindent The position @{text p} in this definition acts as the
+  \emph{first distinct position} of @{text "v\<^sub>1"} and @{text
+  "v\<^sub>2"}, where both values match strings of different length
+  \cite{OkuiSuzuki2010}.  Since at @{text p} the values @{text
+  "v\<^sub>1"} and @{text "v\<^sub>2"} macth different strings, the
+  ordering is irreflexive. Derived from the definition above
+  are the following two orderings:
+  
+  \begin{center}
+  \begin{tabular}{l}
+  @{thm PosOrd_ex_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}\\
+  @{thm PosOrd_ex_eq_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
+  \end{tabular}
+  \end{center}
+
+ While we encountred a number of obstacles for establishing properties like
+ transitivity for the ordering of Sulzmann and Lu (and which we failed
+ to overcome), it is relatively straightforward to establish this
+ property for the ordering by Okui and Suzuki.
+
+ \begin{lemma}[Transitivity]\label{transitivity}
+ @{thm [mode=IfThen] PosOrd_trans[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2" and ?v3.0="v\<^sub>3"]} 
+ \end{lemma}
+
+ \begin{proof} From the assumption we obtain two positions @{text p}
+ and @{text q}, where the values @{text "v\<^sub>1"} and @{text
+ "v\<^sub>2"} (respectively @{text "v\<^sub>2"} and @{text
+ "v\<^sub>3"}) are `distinct'.  Since @{text
+ "\<prec>\<^bsub>lex\<^esub>"} is trichotomous, we need to consider
+ three cases, namely @{term "p = q"}, @{term "p \<sqsubset>lex q"} and
+ @{term "q \<sqsubset>lex p"}. Let us look at the first case.
+ Clearly @{term "pflat_len v\<^sub>2 p < pflat_len v\<^sub>1 p"}
+ and @{term "pflat_len v\<^sub>3 p < pflat_len v\<^sub>2 p"}
+ imply @{term "pflat_len v\<^sub>3 p < pflat_len v\<^sub>1 p"}.
+ It remains to show for a @{term "p' \<in> Pos v\<^sub>1 \<union> Pos v\<^sub>3"}
+ with @{term "p' \<sqsubset>lex p"} that  
+ @{term "pflat_len v\<^sub>1 p' = pflat_len v\<^sub>3 p'"} holds.
+ Suppose @{term "p' \<in> Pos v\<^sub>1"}, then we can infer from the 
+ first assumption that @{term "pflat_len v\<^sub>1 p' = pflat_len v\<^sub>2 p'"}.
+ But this means that @{term "p'"} must be in  @{term "Pos v\<^sub>2"} too.
+ Hence we can use the second assumption and infer  @{term "pflat_len v\<^sub>2 p' = pflat_len v\<^sub>3 p'"}, which concludes
+ this case with @{term "v\<^sub>1 :\<sqsubseteq>val v\<^sub>2"}. 
+ The reasoning in the other cases is similar.\qed
+ \end{proof}
+
+ \noindent We can show that @{term "DUMMY :\<sqsubseteq>val DUMMY"} is
+ a partial order.  Okui and Suzuki also show that it is a linear order
+ for lexical values \cite{OkuiSuzuki2010}, but we have not done
+ this. What we are going to show below is that for a given @{text r}
+ and @{text s}, the ordering has a unique minimal element on the set
+ @{term "LV r s"} , which is the POSIX value we defined in the
+ previous section.
+
+
+ Lemma 1
+
+ @{thm [mode=IfThen] PosOrd_shorterE[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
+
+ but in the other direction only
+
+ @{thm [mode=IfThen] PosOrd_shorterI[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} 
+
+ 
+
+  Next we establish how Okui and Suzuki's ordering relates to our
+  definition of POSIX values.  Given a POSIX value @{text "v\<^sub>1"}
+  for @{text r} and @{text s}, then any other lexical value @{text
+  "v\<^sub>2"} in @{term "LV r s"} is greater or equal than @{text
+  "v\<^sub>1"}:
+
+
+  \begin{theorem}
+  @{thm [mode=IfThen] Posix_PosOrd[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
+  \end{theorem}
+
+  \begin{proof}
+  By induction on our POSIX rules. The two base cases are straightforward: for example 
+  for @{term "v\<^sub>1 = Void"}, we have that @{term "v\<^sub>2 \<in> LV ONE []"} must also 
+  be of the form \mbox{@{term "v\<^sub>2 = Void"}}. Therfore we have @{term "v\<^sub>1 :\<sqsubseteq>val v\<^sub>2"}.
+  The inductive cases are as follows:
+
+  \begin{itemize}
+  \item[$\bullet$] Case @{term "s \<in> (ALT r\<^sub>1 r\<^sub>2) \<rightarrow> (Left w\<^sub>1)"}:
+  In this case @{term "v\<^sub>1 = Left w\<^sub>1"} and the value @{term "v\<^sub>2"} is either 
+  of the form @{term "Left w\<^sub>2"} or @{term "Right w\<^sub>2"}. In the latter case we 
+  can immediately conclude with @{term "v\<^sub>1 :\<sqsubseteq>val v\<^sub>2"} since a @{text Left}-value 
+  with the same underlying string @{text s} is always smaller or equal than a @{text Right}-value.
+  In the former case we have @{term "w\<^sub>2 \<in> LV r\<^sub>1 s"} and can use the induction
+  hypothesis to infer @{term "w\<^sub>1 :\<sqsubseteq>val w\<^sub>2"}. Because @{term "w\<^sub>1"}
+  and @{term "w\<^sub>2"} have the same underlying string @{text s}, we can conclude with 
+  @{term "Left w\<^sub>1 :\<sqsubseteq>val Left w\<^sub>2"}. 
+
+  \item[$\bullet$] Case @{term "s \<in> (ALT r\<^sub>1 r\<^sub>2) \<rightarrow> (Right w\<^sub>1)"}:
+  Similarly for the case where
+  @{term "v\<^sub>1 = Right w\<^sub>1"}.
+
+  \item[$\bullet$]
+  \end{itemize}
+  \end{proof}
+
+  Given a lexical value @{text "v\<^sub>1"}, say, in @{term "LV r s"} for which there does 
+  not exists any smaller value in @{term "LV r s"}, then this value is our POSIX value:
+
+  \begin{theorem}
+  @{thm [mode=IfThen] PosOrd_Posix[where ?v1.0="v\<^sub>1"]}
+  \end{theorem}
+
+  \begin{proof}
+  By induction on @{text r}.
+  \end{proof}
+*}
+
+
 section {* Extensions and Optimisations*}
 
 text {*
@@ -1121,96 +1382,6 @@
   \end{proof} 
 *}
 
-section {* Ordering of Values according to Okui and Suzuki*}
-
-text {*
-
- Positions are lists of natural numbers.
-
- The subvalue at position @{text p}, written @{term "at v p"}, is defined 
-  
-
- \begin{center}
- \begin{tabular}{r@ {\hspace{0mm}}lcl}
- @{term v} &  @{text "\<downharpoonleft>\<^bsub>[]\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(1)}\\
- @{term "Left v"} & @{text "\<downharpoonleft>\<^bsub>0::ps\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(2)}\\
- @{term "Right v"} & @{text "\<downharpoonleft>\<^bsub>1::ps\<^esub>"} & @{text "\<equiv>"} & 
- @{thm (rhs) at.simps(3)[simplified Suc_0_fold]}\\
- @{term "Seq v\<^sub>1 v\<^sub>2"} & @{text "\<downharpoonleft>\<^bsub>0::ps\<^esub>"} & @{text "\<equiv>"} & 
- @{thm (rhs) at.simps(4)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} \\
- @{term "Seq v\<^sub>1 v\<^sub>2"} & @{text "\<downharpoonleft>\<^bsub>1::ps\<^esub>"}
- & @{text "\<equiv>"} & 
- @{thm (rhs) at.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2", simplified Suc_0_fold]} \\
- @{term "Stars vs"} & @{text "\<downharpoonleft>\<^bsub>n::ps\<^esub>"} & @{text "\<equiv>"}& @{thm (rhs) at.simps(6)}\\
- \end{tabular} 
- \end{center}
-
- \begin{center}
- \begin{tabular}{lcl}
- @{thm (lhs) Pos.simps(1)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(1)}\\
- @{thm (lhs) Pos.simps(2)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(2)}\\
- @{thm (lhs) Pos.simps(3)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(3)}\\
- @{thm (lhs) Pos.simps(4)} & @{text "\<equiv>"} & @{thm (rhs) Pos.simps(4)}\\
- @{thm (lhs) Pos.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
-  & @{text "\<equiv>"} 
-  & @{thm (rhs) Pos.simps(5)[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}\\
- @{thm (lhs) Pos_stars} & @{text "\<equiv>"} & @{thm (rhs) Pos_stars}\\
- \end{tabular}
- \end{center}
-
- @{thm pflat_len_def}
-
-
- \begin{center}
- \begin{tabular}{ccc}
- @{thm [mode=Axiom] lex_list.intros(1)}\hspace{1cm} &
- @{thm [mode=Rule] lex_list.intros(2)[where ?ps1.0="ps\<^sub>1" and ?ps2.0="ps\<^sub>2"]}\hspace{1cm} &
- @{thm [mode=Rule] lex_list.intros(3)[where ?p1.0="p\<^sub>1" and ?p2.0="p\<^sub>2" and
-                                            ?ps1.0="ps\<^sub>1" and ?ps2.0="ps\<^sub>2"]}
- \end{tabular}
- \end{center}
-
-
- Main definition by Okui and Suzuki.
-
- \begin{center}
- \begin{tabular}{ccl}
- @{thm (lhs) PosOrd_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} &
- @{text "\<equiv>"} &
- @{term "pflat_len v\<^sub>1 p > pflat_len v\<^sub>2 p"}   and\\
- & & @{term "(\<forall>q \<in> Pos v\<^sub>1 \<union> Pos v\<^sub>2. q \<sqsubset>lex p --> pflat_len v\<^sub>1 q = pflat_len v\<^sub>2 q)"}
- \end{tabular}
- \end{center}
-
- @{thm PosOrd_ex_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
-
- @{thm PosOrd_ex_eq_def[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
-
- Lemma 1
-
- @{thm [mode=IfThen] PosOrd_shorterE[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
-
- but in the other direction only
-
- @{thm [mode=IfThen] PosOrd_shorterI[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]} 
-
- Lemma Transitivity:
-
- @{thm [mode=IfThen] PosOrd_trans[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2" and ?v3.0="v\<^sub>3"]} 
-
-
-*}
-
-text {*
-
- Theorem 1:
-
- @{thm [mode=IfThen] Posix_PosOrd[where ?v1.0="v\<^sub>1" and ?v2.0="v\<^sub>2"]}
-
- Theorem 2:
-
- @{thm [mode=IfThen] PosOrd_Posix[where ?v1.0="v\<^sub>1"]}
-*}
 
 
 section {* The Correctness Argument by Sulzmann and Lu\label{argu} *}
--- a/thys/Journal/document/root.bib	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Journal/document/root.bib	Fri Aug 18 14:51:29 2017 +0100
@@ -308,7 +308,7 @@
 
 
 
-@InProceedings{OkuiSuzuki2013,
+@InProceedings{OkuiSuzuki2010,
   author =       {S.~Okui and T.~Suzuki},
   title =        {{D}isambiguation in {R}egular {E}xpression {M}atching via
                   {P}osition {A}utomata with {A}ugmented {T}ransitions},
@@ -320,3 +320,13 @@
   pages =     {231--240}
 }
 
+
+
+@TechReport{OkuiSuzukiTech,
+  author =       {S.~Okui and T.~Suzuki},
+  title =        {{D}isambiguation in {R}egular {E}xpression {M}atching via
+                  {P}osition {A}utomata with {A}ugmented {T}ransitions},
+  institution =  {University of Aizu},
+  year =         {2013}
+}
+
--- a/thys/Journal/document/root.tex	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Journal/document/root.tex	Fri Aug 18 14:51:29 2017 +0100
@@ -41,11 +41,16 @@
 \renewcommand{\thefootnote}{$\star$} \footnotetext[1]{This paper is a
   revised and expanded version of \cite{AusafDyckhoffUrban2016}.
   Compared with that paper we give a second definition for POSIX
-  values introduced by Okui Suzuki \cite{OkuiSuzuki2013} and prove that it is
+  values introduced by Okui Suzuki \cite{OkuiSuzuki2010,OkuiSuzukiTech}
+  and prove that it is
   equivalent to our original one. This
   second definition is based on an ordering of values and very similar to,
   but not equivalent with, the
-  definition given by Sulzmann and Lu~\cite{Sulzmann2014}. We also
+  definition given by Sulzmann and Lu~\cite{Sulzmann2014}.
+  The advantage of the definition based on the
+  ordering is that it implements more directly the informal rules from the
+  POSIX standard.
+  We also
   extend our results to additional constructors of regular
   expressions.}  \renewcommand{\thefootnote}{\arabic{footnote}}
 
@@ -75,9 +80,7 @@
 second part we show that $(iii)$ our inductive definition of a POSIX
 value is equivalent to an alternative definition by Okui and Suzuki
 which identifies POSIX values as least elements according to an
-ordering of values. The advantage of the definition based on the
-ordering is that it implements more directly the informal rules from the
-POSIX standard.\smallskip
+ordering of values. \smallskip
 
 {\bf Keywords:} POSIX matching, Derivatives of Regular Expressions,
 Isabelle/HOL
--- a/thys/Lexer.thy	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Lexer.thy	Fri Aug 18 14:51:29 2017 +0100
@@ -38,7 +38,7 @@
 
 lemma mkeps_nullable:
   assumes "nullable(r)" 
-  shows "\<turnstile> mkeps r : r"
+  shows "\<Turnstile> mkeps r : r"
 using assms
 by (induct rule: nullable.induct) 
    (auto intro: Prf.intros)
@@ -49,22 +49,25 @@
 using assms
 by (induct rule: nullable.induct) (auto)
 
-lemma Prf_injval:
-  assumes "\<turnstile> v : der c r" 
-  shows "\<turnstile> (injval r c v) : r"
-using assms
-apply(induct r arbitrary: c v rule: rexp.induct)
-apply(auto intro!: Prf.intros mkeps_nullable elim!: Prf_elims split: if_splits)
-done
-
 lemma Prf_injval_flat:
-  assumes "\<turnstile> v : der c r" 
+  assumes "\<Turnstile> v : der c r" 
   shows "flat (injval r c v) = c # (flat v)"
 using assms
 apply(induct arbitrary: v rule: der.induct)
 apply(auto elim!: Prf_elims intro: mkeps_flat split: if_splits)
 done
 
+lemma Prf_injval:
+  assumes "\<Turnstile> v : der c r" 
+  shows "\<Turnstile> (injval r c v) : r"
+using assms
+apply(induct r arbitrary: c v rule: rexp.induct)
+apply(auto intro!: Prf.intros mkeps_nullable elim!: Prf_elims split: if_splits)
+apply(simp add: Prf_injval_flat)
+done
+
+
+
 text {*
   Mkeps and injval produce, or preserve, Posix values.
 *}
--- a/thys/Positions.thy	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Positions.thy	Fri Aug 18 14:51:29 2017 +0100
@@ -1,6 +1,6 @@
    
 theory Positions
-  imports "Spec" 
+  imports "Spec" "Lexer" 
 begin
 
 section {* Positions in Values *}
@@ -38,30 +38,9 @@
   shows "[] \<in> Pos v"
 by (induct v rule: Pos.induct)(auto)
 
-fun intlen :: "'a list \<Rightarrow> int"
-where
-  "intlen [] = 0"
-| "intlen (x # xs) = 1 + intlen xs"
-
-lemma intlen_int:
-  shows "intlen xs = int (length xs)"
-by (induct xs)(simp_all)
+abbreviation
+  "intlen vs \<equiv> int (length vs)"
 
-lemma intlen_bigger:
-  shows "0 \<le> intlen xs"
-by (induct xs)(auto)
-
-lemma intlen_append:
-  shows "intlen (xs @ ys) = intlen xs + intlen ys"
-by (simp add: intlen_int)
-
-lemma intlen_length:
-  shows "intlen xs < intlen ys \<longleftrightarrow> length xs < length ys"
-by (simp add: intlen_int)
-
-lemma intlen_length_eq:
-  shows "intlen xs = intlen ys \<longleftrightarrow> length xs = length ys"
-by (simp add: intlen_int)
 
 definition pflat_len :: "val \<Rightarrow> nat list => int"
 where
@@ -165,27 +144,118 @@
   "v1 :\<sqsubseteq>val v2 \<equiv> v1 :\<sqsubset>val v2 \<or> v1 = v2"
 
 
+lemma PosOrd_trans:
+  assumes "v1 :\<sqsubset>val v2" "v2 :\<sqsubset>val v3"
+  shows "v1 :\<sqsubset>val v3"
+proof -
+  from assms obtain p p'
+    where as: "v1 \<sqsubset>val p v2" "v2 \<sqsubset>val p' v3" unfolding PosOrd_ex_def by blast
+  then have pos: "p \<in> Pos v1" "p' \<in> Pos v2" unfolding PosOrd_def pflat_len_def
+    by (smt not_int_zless_negative)+
+  have "p = p' \<or> p \<sqsubset>lex p' \<or> p' \<sqsubset>lex p"
+    by (rule lex_trichotomous)
+  moreover
+    { assume "p = p'"
+      with as have "v1 \<sqsubset>val p v3" unfolding PosOrd_def pflat_len_def
+      by (smt Un_iff)
+      then have " v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
+    }   
+  moreover
+    { assume "p \<sqsubset>lex p'"
+      with as have "v1 \<sqsubset>val p v3" unfolding PosOrd_def pflat_len_def
+      by (smt Un_iff lex_trans)
+      then have " v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
+    }
+  moreover
+    { assume "p' \<sqsubset>lex p"
+      with as have "v1 \<sqsubset>val p' v3" unfolding PosOrd_def
+      by (smt Un_iff lex_trans pflat_len_def)
+      then have "v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
+    }
+  ultimately show "v1 :\<sqsubset>val v3" by blast
+qed
+
+lemma PosOrd_irrefl:
+  assumes "v :\<sqsubset>val v"
+  shows "False"
+using assms unfolding PosOrd_ex_def PosOrd_def
+by auto
+
+lemma PosOrd_assym:
+  assumes "v1 :\<sqsubset>val v2" 
+  shows "\<not>(v2 :\<sqsubset>val v1)"
+using assms
+using PosOrd_irrefl PosOrd_trans by blast 
+
+text {*
+  :\<sqsubseteq>val and :\<sqsubset>val are partial orders.
+*}
+
+lemma PosOrd_ordering:
+  shows "ordering (\<lambda>v1 v2. v1 :\<sqsubseteq>val v2) (\<lambda> v1 v2. v1 :\<sqsubset>val v2)"
+unfolding ordering_def PosOrd_ex_eq_def
+apply(auto)
+using PosOrd_irrefl apply blast
+using PosOrd_assym apply blast
+using PosOrd_trans by blast
+
+lemma PosOrd_order:
+  shows "class.order (\<lambda>v1 v2. v1 :\<sqsubseteq>val v2) (\<lambda> v1 v2. v1 :\<sqsubset>val v2)"
+using PosOrd_ordering
+apply(simp add: class.order_def class.preorder_def class.order_axioms_def)
+unfolding ordering_def
+by blast
+
+
+lemma PosOrd_ex_eq2:
+  shows "v1 :\<sqsubset>val v2 \<longleftrightarrow> (v1 :\<sqsubseteq>val v2 \<and> v1 \<noteq> v2)"
+using PosOrd_ordering 
+unfolding ordering_def
+by auto
+
+lemma PosOrdeq_trans:
+  assumes "v1 :\<sqsubseteq>val v2" "v2 :\<sqsubseteq>val v3"
+  shows "v1 :\<sqsubseteq>val v3"
+using assms PosOrd_ordering 
+unfolding ordering_def
+by blast
+
+lemma PosOrdeq_antisym:
+  assumes "v1 :\<sqsubseteq>val v2" "v2 :\<sqsubseteq>val v1"
+  shows "v1 = v2"
+using assms PosOrd_ordering 
+unfolding ordering_def
+by blast
+
+lemma PosOrdeq_refl:
+  shows "v :\<sqsubseteq>val v" 
+unfolding PosOrd_ex_eq_def
+by auto
+
+
+
+
 lemma PosOrd_shorterE:
   assumes "v1 :\<sqsubset>val v2" 
   shows "length (flat v2) \<le> length (flat v1)"
 using assms unfolding PosOrd_ex_def PosOrd_def
-apply(auto simp add: pflat_len_def intlen_int split: if_splits)
+apply(auto simp add: pflat_len_def split: if_splits)
 apply (metis Pos_empty Un_iff at.simps(1) eq_iff lex_simps(1) nat_less_le)
 by (metis Pos_empty UnI2 at.simps(1) lex_simps(2) lex_trichotomous linear)
 
 lemma PosOrd_shorterI:
   assumes "length (flat v2) < length (flat v1)"
-  shows "v1 :\<sqsubset>val v2" 
-using assms
-unfolding PosOrd_ex_def
-by (metis intlen_length lex_simps(2) pflat_len_simps(9) PosOrd_def)
+  shows "v1 :\<sqsubset>val v2"
+unfolding PosOrd_ex_def PosOrd_def pflat_len_def 
+using assms Pos_empty by force
 
 lemma PosOrd_spreI:
   assumes "flat v' \<sqsubset>spre flat v"
   shows "v :\<sqsubset>val v'" 
 using assms
 apply(rule_tac PosOrd_shorterI)
-by (metis append_eq_conv_conj le_less_linear prefix_list_def sprefix_list_def take_all)
+unfolding prefix_list_def sprefix_list_def
+by (metis append_Nil2 append_eq_conv_conj drop_all le_less_linear)
 
 
 lemma PosOrd_Left_Right:
@@ -194,7 +264,7 @@
 unfolding PosOrd_ex_def
 apply(rule_tac x="[0]" in exI)
 using assms 
-apply(auto simp add: PosOrd_def pflat_len_simps intlen_int)
+apply(auto simp add: PosOrd_def pflat_len_simps)
 done
 
 lemma PosOrd_Left_eq:
@@ -219,7 +289,7 @@
 
 lemma PosOrd_RightI:
   assumes "v :\<sqsubset>val v'" "flat v = flat v'"
-  shows "(Right v) :\<sqsubset>val (Right v')" 
+  shows "Right v :\<sqsubset>val Right v'" 
 using assms(1)
 unfolding PosOrd_ex_def
 apply(auto)
@@ -229,7 +299,7 @@
 done
 
 lemma PosOrd_RightE:
-  assumes "(Right v1) :\<sqsubset>val (Right v2)"
+  assumes "Right v1 :\<sqsubset>val Right v2"
   shows "v1 :\<sqsubset>val v2"
 using assms
 apply(simp add: PosOrd_ex_def)
@@ -258,7 +328,7 @@
 
 lemma PosOrd_SeqI1:
   assumes "v1 :\<sqsubset>val v1'" "flat (Seq v1 v2) = flat (Seq v1' v2')"
-  shows "(Seq v1 v2) :\<sqsubset>val (Seq v1' v2')" 
+  shows "Seq v1 v2 :\<sqsubset>val Seq v1' v2'" 
 using assms(1)
 apply(subst (asm) PosOrd_ex_def)
 apply(subst (asm) PosOrd_def)
@@ -275,12 +345,12 @@
 apply(simp add: pflat_len_simps)
 using assms(2)
 apply(simp)
-apply(auto simp add: pflat_len_simps)[2]
-done
+apply(auto simp add: pflat_len_simps)
+by (metis length_append of_nat_add)
 
 lemma PosOrd_SeqI2:
   assumes "v2 :\<sqsubset>val v2'" "flat v2 = flat v2'"
-  shows "(Seq v v2) :\<sqsubset>val (Seq v v2')" 
+  shows "Seq v v2 :\<sqsubset>val Seq v v2'" 
 using assms(1)
 apply(subst (asm) PosOrd_ex_def)
 apply(subst (asm) PosOrd_def)
@@ -301,21 +371,21 @@
 done
 
 lemma PosOrd_SeqE:
-  assumes "(Seq v1 v2) :\<sqsubset>val (Seq v1' v2')" 
+  assumes "Seq v1 v2 :\<sqsubset>val Seq v1' v2'" 
   shows "v1 :\<sqsubset>val v1' \<or> v2 :\<sqsubset>val v2'"
 using assms
 apply(simp add: PosOrd_ex_def)
 apply(erule exE)
 apply(case_tac p)
 apply(simp add: PosOrd_def)
-apply(auto simp add: pflat_len_simps intlen_append)[1]
+apply(auto simp add: pflat_len_simps)[1]
 apply(rule_tac x="[]" in exI)
 apply(drule_tac x="[]" in spec)
 apply(simp add: Pos_empty pflat_len_simps)
 apply(case_tac a)
 apply(rule disjI1)
 apply(simp add: PosOrd_def)
-apply(auto simp add: pflat_len_simps intlen_append)[1]
+apply(auto simp add: pflat_len_simps)[1]
 apply(rule_tac x="list" in exI)
 apply(simp)
 apply(rule ballI)
@@ -326,7 +396,7 @@
 apply(case_tac nat)
 apply(rule disjI2)
 apply(simp add: PosOrd_def)
-apply(auto simp add: pflat_len_simps intlen_append)
+apply(auto simp add: pflat_len_simps)
 apply(rule_tac x="list" in exI)
 apply(simp add: Pos_empty)
 apply(rule ballI)
@@ -342,8 +412,8 @@
 done
 
 lemma PosOrd_StarsI:
-  assumes "v1 :\<sqsubset>val v2" "flat (Stars (v1#vs1)) = flat (Stars (v2#vs2))"
-  shows "(Stars (v1#vs1)) :\<sqsubset>val (Stars (v2#vs2))" 
+  assumes "v1 :\<sqsubset>val v2" "flats (v1#vs1) = flats (v2#vs2)"
+  shows "Stars (v1#vs1) :\<sqsubset>val Stars (v2#vs2)" 
 using assms(1)
 apply(subst (asm) PosOrd_ex_def)
 apply(subst (asm) PosOrd_def)
@@ -353,13 +423,13 @@
 apply(rule_tac x="0#p" in exI)
 apply(simp add: pflat_len_Stars_simps pflat_len_simps)
 using assms(2)
-apply(simp add: pflat_len_simps intlen_append)
+apply(simp add: pflat_len_simps)
 apply(auto simp add: pflat_len_Stars_simps pflat_len_simps)
-done
+by (metis length_append of_nat_add)
 
 lemma PosOrd_StarsI2:
-  assumes "(Stars vs1) :\<sqsubset>val (Stars vs2)" "flat (Stars vs1) = flat (Stars vs2)"
-  shows "(Stars (v#vs1)) :\<sqsubset>val (Stars (v#vs2))" 
+  assumes "Stars vs1 :\<sqsubset>val Stars vs2" "flats vs1 = flats vs2"
+  shows "Stars (v#vs1) :\<sqsubset>val Stars (v#vs2)" 
 using assms(1)
 apply(subst (asm) PosOrd_ex_def)
 apply(subst (asm) PosOrd_def)
@@ -368,13 +438,8 @@
 apply(subst PosOrd_def)
 apply(case_tac p)
 apply(simp add: pflat_len_simps)
-apply(rule_tac x="[]" in exI)
-apply(simp add: pflat_len_Stars_simps pflat_len_simps intlen_append)
 apply(rule_tac x="Suc a#list" in exI)
-apply(simp add: pflat_len_Stars_simps pflat_len_simps)
-using assms(2)
-apply(simp add: pflat_len_simps intlen_append)
-apply(auto simp add: pflat_len_Stars_simps pflat_len_simps)
+apply(auto simp add: pflat_len_Stars_simps pflat_len_simps assms(2))
 done
 
 lemma PosOrd_Stars_appendI:
@@ -394,7 +459,7 @@
 apply(erule exE)
 apply(case_tac p)
 apply(simp)
-apply(simp add: PosOrd_def pflat_len_simps intlen_append)
+apply(simp add: PosOrd_def pflat_len_simps)
 apply(subst PosOrd_ex_def)
 apply(rule_tac x="[]" in exI)
 apply(simp add: PosOrd_def pflat_len_simps Pos_empty)
@@ -405,19 +470,19 @@
 apply(clarify)
 apply(simp add: PosOrd_ex_def)
 apply(rule_tac x="nat#list" in exI)
-apply(auto simp add: PosOrd_def pflat_len_simps intlen_append)[1]
+apply(auto simp add: PosOrd_def pflat_len_simps)[1]
 apply(case_tac q)
-apply(simp add: PosOrd_def pflat_len_simps intlen_append)
+apply(simp add: PosOrd_def pflat_len_simps)
 apply(clarify)
 apply(drule_tac x="Suc a # lista" in bspec)
 apply(simp)
-apply(auto simp add: PosOrd_def pflat_len_simps intlen_append)[1]
+apply(auto simp add: PosOrd_def pflat_len_simps)[1]
 apply(case_tac q)
-apply(simp add: PosOrd_def pflat_len_simps intlen_append)
+apply(simp add: PosOrd_def pflat_len_simps)
 apply(clarify)
 apply(drule_tac x="Suc a # lista" in bspec)
 apply(simp)
-apply(auto simp add: PosOrd_def pflat_len_simps intlen_append)[1]
+apply(auto simp add: PosOrd_def pflat_len_simps)[1]
 done
 
 lemma PosOrd_Stars_appendE:
@@ -439,42 +504,6 @@
 apply(auto)
 done
 
-lemma PosOrd_trans:
-  assumes "v1 :\<sqsubset>val v2" "v2 :\<sqsubset>val v3"
-  shows "v1 :\<sqsubset>val v3"
-proof -
-  from assms obtain p p'
-    where as: "v1 \<sqsubset>val p v2" "v2 \<sqsubset>val p' v3" unfolding PosOrd_ex_def by blast
-  have "p = p' \<or> p \<sqsubset>lex p' \<or> p' \<sqsubset>lex p"
-    by (rule lex_trichotomous)
-  moreover
-    { assume "p = p'"
-      with as have "v1 \<sqsubset>val p v3" unfolding PosOrd_def pflat_len_def
-      by fastforce
-      then have " v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
-    }   
-  moreover
-    { assume "p \<sqsubset>lex p'"
-      with as have "v1 \<sqsubset>val p v3" unfolding PosOrd_def pflat_len_def
-      by (smt Un_iff lex_trans)
-      then have " v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
-    }
-  moreover
-    { assume "p' \<sqsubset>lex p"
-      with as have "v1 \<sqsubset>val p' v3" unfolding PosOrd_def
-      by (smt Un_iff intlen_bigger lex_trans pflat_len_def)
-      then have "v1 :\<sqsubset>val v3" unfolding PosOrd_ex_def by blast
-    }
-  ultimately show "v1 :\<sqsubset>val v3" by blast
-qed
-
-
-lemma PosOrd_irrefl:
-  assumes "v :\<sqsubset>val v"
-  shows "False"
-using assms unfolding PosOrd_ex_def PosOrd_def
-by auto
-
 lemma PosOrd_almost_trichotomous:
   shows "v1 :\<sqsubset>val v2 \<or> v2 :\<sqsubset>val v1 \<or> (intlen (flat v1) = intlen (flat v2))"
 apply(auto simp add: PosOrd_ex_def)
@@ -485,12 +514,6 @@
 apply(auto simp add: Pos_empty pflat_len_simps)
 done
 
-lemma WW1:
-  assumes "v1 :\<sqsubset>val v2" "v2 :\<sqsubset>val v1"
-  shows "False"
-using assms
-apply(auto simp add: PosOrd_ex_def PosOrd_def)
-using assms PosOrd_irrefl PosOrd_trans by blast
 
 lemma PosOrd_SeqE2:
   assumes "(Seq v1 v2) :\<sqsubset>val (Seq v1' v2')" "flat (Seq v1 v2) = flat (Seq v1' v2')"
@@ -512,8 +535,8 @@
 apply(auto simp add: PosOrd_def pflat_len_simps)
 apply(case_tac a)
 apply(auto simp add: PosOrd_def pflat_len_simps)
-apply (metis PosOrd_SeqI1 PosOrd_almost_trichotomous PosOrd_def PosOrd_ex_def WW1 assms(1) assms(2))
-by (metis PosOrd_SeqI1 PosOrd_almost_trichotomous PosOrd_def PosOrd_ex_def WW1 assms(1) assms(2))
+apply (metis PosOrd_SeqI1 PosOrd_def PosOrd_ex_def PosOrd_shorterI PosOrd_assym assms less_linear)
+by (metis PosOrd_SeqI1 PosOrd_almost_trichotomous PosOrd_def PosOrd_ex_def PosOrd_assym assms of_nat_eq_iff)
 
 lemma PosOrd_SeqE4:
   assumes "(Seq v1 v2) :\<sqsubset>val (Seq v1' v2')" "flat (Seq v1 v2) = flat (Seq v1' v2')"
@@ -531,7 +554,7 @@
 apply(auto)
 apply(case_tac "length (flat v1') < length (flat v1)")
 using PosOrd_shorterI apply blast
-by (metis PosOrd_SeqI1 PosOrd_shorterI WW1 antisym_conv3 append_eq_append_conv assms(2))
+by (metis PosOrd_SeqI1 PosOrd_shorterI PosOrd_assym antisym_conv3 append_eq_append_conv assms(2))
 
 
 
@@ -539,39 +562,39 @@
 
 
 lemma Posix_PosOrd:
-  assumes "s \<in> r \<rightarrow> v1" "v2 \<in> CV r s" 
+  assumes "s \<in> r \<rightarrow> v1" "v2 \<in> LV r s" 
   shows "v1 :\<sqsubseteq>val v2"
 using assms
 proof (induct arbitrary: v2 rule: Posix.induct)
   case (Posix_ONE v)
-  have "v \<in> CV ONE []" by fact
+  have "v \<in> LV ONE []" by fact
   then have "v = Void"
-    by (simp add: CV_simps)
+    by (simp add: LV_simps)
   then show "Void :\<sqsubseteq>val v"
     by (simp add: PosOrd_ex_eq_def)
 next
   case (Posix_CHAR c v)
-  have "v \<in> CV (CHAR c) [c]" by fact
+  have "v \<in> LV (CHAR c) [c]" by fact
   then have "v = Char c"
-    by (simp add: CV_simps)
+    by (simp add: LV_simps)
   then show "Char c :\<sqsubseteq>val v"
     by (simp add: PosOrd_ex_eq_def)
 next
   case (Posix_ALT1 s r1 v r2 v2)
   have as1: "s \<in> r1 \<rightarrow> v" by fact
-  have IH: "\<And>v2. v2 \<in> CV r1 s \<Longrightarrow> v :\<sqsubseteq>val v2" by fact
-  have "v2 \<in> CV (ALT r1 r2) s" by fact
+  have IH: "\<And>v2. v2 \<in> LV r1 s \<Longrightarrow> v :\<sqsubseteq>val v2" by fact
+  have "v2 \<in> LV (ALT r1 r2) s" by fact
   then have "\<Turnstile> v2 : ALT r1 r2" "flat v2 = s"
-    by(auto simp add: CV_def prefix_list_def)
+    by(auto simp add: LV_def prefix_list_def)
   then consider
     (Left) v3 where "v2 = Left v3" "\<Turnstile> v3 : r1" "flat v3 = s" 
   | (Right) v3 where "v2 = Right v3" "\<Turnstile> v3 : r2" "flat v3 = s"
-  by (auto elim: CPrf.cases)
+  by (auto elim: Prf.cases)
   then show "Left v :\<sqsubseteq>val v2"
   proof(cases)
      case (Left v3)
-     have "v3 \<in> CV r1 s" using Left(2,3) 
-       by (auto simp add: CV_def prefix_list_def)
+     have "v3 \<in> LV r1 s" using Left(2,3) 
+       by (auto simp add: LV_def prefix_list_def)
      with IH have "v :\<sqsubseteq>val v3" by simp
      moreover
      have "flat v3 = flat v" using as1 Left(3)
@@ -583,27 +606,28 @@
      case (Right v3)
      have "flat v3 = flat v" using as1 Right(3)
        by (simp add: Posix1(2)) 
-     then have "Left v :\<sqsubseteq>val Right v3" using Right(3) as1 
-       by (auto simp add: PosOrd_ex_eq_def PosOrd_Left_Right)
+     then have "Left v :\<sqsubseteq>val Right v3" 
+       unfolding PosOrd_ex_eq_def
+       by (simp add: PosOrd_Left_Right)
      then show "Left v :\<sqsubseteq>val v2" unfolding Right .
   qed
 next
   case (Posix_ALT2 s r2 v r1 v2)
   have as1: "s \<in> r2 \<rightarrow> v" by fact
   have as2: "s \<notin> L r1" by fact
-  have IH: "\<And>v2. v2 \<in> CV r2 s \<Longrightarrow> v :\<sqsubseteq>val v2" by fact
-  have "v2 \<in> CV (ALT r1 r2) s" by fact
+  have IH: "\<And>v2. v2 \<in> LV r2 s \<Longrightarrow> v :\<sqsubseteq>val v2" by fact
+  have "v2 \<in> LV (ALT r1 r2) s" by fact
   then have "\<Turnstile> v2 : ALT r1 r2" "flat v2 = s"
-    by(auto simp add: CV_def prefix_list_def)
+    by(auto simp add: LV_def prefix_list_def)
   then consider
     (Left) v3 where "v2 = Left v3" "\<Turnstile> v3 : r1" "flat v3 = s" 
   | (Right) v3 where "v2 = Right v3" "\<Turnstile> v3 : r2" "flat v3 = s"
-  by (auto elim: CPrf.cases)
+  by (auto elim: Prf.cases)
   then show "Right v :\<sqsubseteq>val v2"
   proof (cases)
     case (Right v3)
-     have "v3 \<in> CV r2 s" using Right(2,3) 
-       by (auto simp add: CV_def prefix_list_def)
+     have "v3 \<in> LV r2 s" using Right(2,3) 
+       by (auto simp add: LV_def prefix_list_def)
      with IH have "v :\<sqsubseteq>val v3" by simp
      moreover
      have "flat v3 = flat v" using as1 Right(3)
@@ -613,34 +637,34 @@
      then show "Right v :\<sqsubseteq>val v2" unfolding Right .
   next
      case (Left v3)
-     have "v3 \<in> CV r1 s" using Left(2,3) as2  
-       by (auto simp add: CV_def prefix_list_def)
+     have "v3 \<in> LV r1 s" using Left(2,3) as2  
+       by (auto simp add: LV_def prefix_list_def)
      then have "flat v3 = flat v \<and> \<Turnstile> v3 : r1" using as1 Left(3)
-       by (simp add: Posix1(2) CV_def) 
+       by (simp add: Posix1(2) LV_def) 
      then have "False" using as1 as2 Left
-       by (auto simp add: Posix1(2) L_flat_Prf1 Prf_CPrf)
+       by (auto simp add: Posix1(2) L_flat_Prf1)
      then show "Right v :\<sqsubseteq>val v2" by simp
   qed
 next 
   case (Posix_SEQ s1 r1 v1 s2 r2 v2 v3)
   have "s1 \<in> r1 \<rightarrow> v1" "s2 \<in> r2 \<rightarrow> v2" by fact+
   then have as1: "s1 = flat v1" "s2 = flat v2" by (simp_all add: Posix1(2))
-  have IH1: "\<And>v3. v3 \<in> CV r1 s1 \<Longrightarrow> v1 :\<sqsubseteq>val v3" by fact
-  have IH2: "\<And>v3. v3 \<in> CV r2 s2 \<Longrightarrow> v2 :\<sqsubseteq>val v3" by fact
+  have IH1: "\<And>v3. v3 \<in> LV r1 s1 \<Longrightarrow> v1 :\<sqsubseteq>val v3" by fact
+  have IH2: "\<And>v3. v3 \<in> LV r2 s2 \<Longrightarrow> v2 :\<sqsubseteq>val v3" by fact
   have cond: "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> L r1 \<and> s\<^sub>4 \<in> L r2)" by fact
-  have "v3 \<in> CV (SEQ r1 r2) (s1 @ s2)" by fact
+  have "v3 \<in> LV (SEQ r1 r2) (s1 @ s2)" by fact
   then obtain v3a v3b where eqs:
     "v3 = Seq v3a v3b" "\<Turnstile> v3a : r1" "\<Turnstile> v3b : r2"
     "flat v3a @ flat v3b = s1 @ s2" 
-    by (force simp add: prefix_list_def CV_def elim: CPrf.cases)
+    by (force simp add: prefix_list_def LV_def elim: Prf.cases)
   with cond have "flat v3a \<sqsubseteq>pre s1" unfolding prefix_list_def
-    by (smt L_flat_Prf1 Prf_CPrf append_eq_append_conv2 append_self_conv)
+    by (smt L_flat_Prf1 append_eq_append_conv2 append_self_conv)
   then have "flat v3a \<sqsubset>spre s1 \<or> (flat v3a = s1 \<and> flat v3b = s2)" using eqs
     by (simp add: sprefix_list_def append_eq_conv_conj)
   then have q2: "v1 :\<sqsubset>val v3a \<or> (flat v3a = s1 \<and> flat v3b = s2)" 
     using PosOrd_spreI as1(1) eqs by blast
-  then have "v1 :\<sqsubset>val v3a \<or> (v3a \<in> CV r1 s1 \<and> v3b \<in> CV r2 s2)" using eqs(2,3)
-    by (auto simp add: CV_def)
+  then have "v1 :\<sqsubset>val v3a \<or> (v3a \<in> LV r1 s1 \<and> v3b \<in> LV r2 s2)" using eqs(2,3)
+    by (auto simp add: LV_def)
   then have "v1 :\<sqsubset>val v3a \<or> (v1 :\<sqsubseteq>val v3a \<and> v2 :\<sqsubseteq>val v3b)" using IH1 IH2 by blast         
   then have "Seq v1 v2 :\<sqsubseteq>val Seq v3a v3b" using eqs q2 as1
     unfolding  PosOrd_ex_eq_def by (auto simp add: PosOrd_SeqI1 PosOrd_SeqI2) 
@@ -649,43 +673,43 @@
   case (Posix_STAR1 s1 r v s2 vs v3) 
   have "s1 \<in> r \<rightarrow> v" "s2 \<in> STAR r \<rightarrow> Stars vs" by fact+
   then have as1: "s1 = flat v" "s2 = flat (Stars vs)" by (auto dest: Posix1(2))
-  have IH1: "\<And>v3. v3 \<in> CV r s1 \<Longrightarrow> v :\<sqsubseteq>val v3" by fact
-  have IH2: "\<And>v3. v3 \<in> CV (STAR r) s2 \<Longrightarrow> Stars vs :\<sqsubseteq>val v3" by fact
+  have IH1: "\<And>v3. v3 \<in> LV r s1 \<Longrightarrow> v :\<sqsubseteq>val v3" by fact
+  have IH2: "\<And>v3. v3 \<in> LV (STAR r) s2 \<Longrightarrow> Stars vs :\<sqsubseteq>val v3" by fact
   have cond: "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> L r \<and> s\<^sub>4 \<in> L (STAR r))" by fact
   have cond2: "flat v \<noteq> []" by fact
-  have "v3 \<in> CV (STAR r) (s1 @ s2)" by fact
+  have "v3 \<in> LV (STAR r) (s1 @ s2)" by fact
   then consider 
     (NonEmpty) v3a vs3 where "v3 = Stars (v3a # vs3)" 
     "\<Turnstile> v3a : r" "\<Turnstile> Stars vs3 : STAR r"
     "flat (Stars (v3a # vs3)) = s1 @ s2"
   | (Empty) "v3 = Stars []"
-  unfolding CV_def
+  unfolding LV_def  
   apply(auto)
-  apply(erule CPrf.cases)
+  apply(erule Prf.cases)
   apply(simp_all)
   apply(auto)[1]
   apply(case_tac vs)
   apply(auto)
-  using CPrf.intros(6) by blast
-  then show "Stars (v # vs) :\<sqsubseteq>val v3" (* HERE *)
+  using Prf.intros(6) by blast
+  then show "Stars (v # vs) :\<sqsubseteq>val v3" 
     proof (cases)
       case (NonEmpty v3a vs3)
       have "flat (Stars (v3a # vs3)) = s1 @ s2" using NonEmpty(4) . 
       with cond have "flat v3a \<sqsubseteq>pre s1" using NonEmpty(2,3)
         unfolding prefix_list_def
-        by (smt L_flat_Prf1 Prf_CPrf append_Nil2 append_eq_append_conv2 flat.simps(7)) 
+        by (smt L_flat_Prf1 append_Nil2 append_eq_append_conv2 flat.simps(7)) 
       then have "flat v3a \<sqsubset>spre s1 \<or> (flat v3a = s1 \<and> flat (Stars vs3) = s2)" using NonEmpty(4)
         by (simp add: sprefix_list_def append_eq_conv_conj)
       then have q2: "v :\<sqsubset>val v3a \<or> (flat v3a = s1 \<and> flat (Stars vs3) = s2)" 
         using PosOrd_spreI as1(1) NonEmpty(4) by blast
-      then have "v :\<sqsubset>val v3a \<or> (v3a \<in> CV r s1 \<and> Stars vs3 \<in> CV (STAR r) s2)" 
-        using NonEmpty(2,3) by (auto simp add: CV_def)
+      then have "v :\<sqsubset>val v3a \<or> (v3a \<in> LV r s1 \<and> Stars vs3 \<in> LV (STAR r) s2)" 
+        using NonEmpty(2,3) by (auto simp add: LV_def)
       then have "v :\<sqsubset>val v3a \<or> (v :\<sqsubseteq>val v3a \<and> Stars vs :\<sqsubseteq>val Stars vs3)" using IH1 IH2 by blast
       then have "v :\<sqsubset>val v3a \<or> (v = v3a \<and> Stars vs :\<sqsubseteq>val Stars vs3)" 
          unfolding PosOrd_ex_eq_def by auto     
       then have "Stars (v # vs) :\<sqsubseteq>val Stars (v3a # vs3)" using NonEmpty(4) q2 as1
         unfolding  PosOrd_ex_eq_def
-        by (metis PosOrd_StarsI PosOrd_StarsI2 flat.simps(7) val.inject(5))
+        using PosOrd_StarsI PosOrd_StarsI2 by auto 
       then show "Stars (v # vs) :\<sqsubseteq>val v3" unfolding NonEmpty by blast
     next 
       case Empty
@@ -696,9 +720,9 @@
     qed      
 next 
   case (Posix_STAR2 r v2)
-  have "v2 \<in> CV (STAR r) []" by fact
+  have "v2 \<in> LV (STAR r) []" by fact
   then have "v2 = Stars []" 
-    unfolding CV_def by (auto elim: CPrf.cases) 
+    unfolding LV_def by (auto elim: Prf.cases) 
   then show "Stars [] :\<sqsubseteq>val v2"
   by (simp add: PosOrd_ex_eq_def)
 qed
@@ -706,7 +730,7 @@
 
 lemma Posix_PosOrd_reverse:
   assumes "s \<in> r \<rightarrow> v1" 
-  shows "\<not>(\<exists>v2 \<in> CV r s. v2 :\<sqsubset>val v1)"
+  shows "\<not>(\<exists>v2 \<in> LV r s. v2 :\<sqsubset>val v1)"
 using assms
 by (metis Posix_PosOrd less_irrefl PosOrd_def 
     PosOrd_ex_eq_def PosOrd_ex_def PosOrd_trans)
@@ -729,7 +753,7 @@
              \<Longrightarrow> flat (Stars vs) \<in> STAR r \<rightarrow> Stars vs" by fact
   have as2: "\<forall>v\<in>set (v # vs). flat v \<in> r \<rightarrow> v \<and> flat v \<noteq> []" by fact
   have as3: "\<not> (\<exists>vs2\<in>LV (STAR r) (flat (Stars (v # vs))). vs2 :\<sqsubset>val Stars (v # vs))" by fact
-  have "flat v \<in> r \<rightarrow> v" using as2 by simp
+  have "flat v \<in> r \<rightarrow> v" "flat v \<noteq> []" using as2 by auto
   moreover
   have  "flat (Stars vs) \<in> STAR r \<rightarrow> Stars vs" 
     proof (rule IH)
@@ -742,11 +766,14 @@
         apply(erule Prf.cases)
         apply(simp_all)
         apply(drule_tac x="Stars (v # vs)" in bspec)
-        apply(simp add: LV_def CV_def)
-        using Posix_Prf Prf.intros(6) calculation
+        apply(simp add: LV_def)
+        using Posix_LV Prf.intros(6) calculation
         apply(rule_tac Prf.intros)
         apply(simp add:)
+        prefer 2
         apply (simp add: PosOrd_StarsI2)
+        apply(drule Posix_LV) 
+        apply(simp add: LV_def)
         done
     qed
   moreover
@@ -778,48 +805,44 @@
 
 section {* The Smallest Value is indeed the Posix Value *}
 
-text {*
-  The next lemma seems to require LV instead of CV in the Star-case.
-*}
-
 lemma PosOrd_Posix:
-  assumes "v1 \<in> CV r s" "\<forall>v\<^sub>2 \<in> LV r s. \<not> v\<^sub>2 :\<sqsubset>val v1"
+  assumes "v1 \<in> LV r s" "\<forall>v\<^sub>2 \<in> LV r s. \<not> v\<^sub>2 :\<sqsubset>val v1"
   shows "s \<in> r \<rightarrow> v1" 
 using assms
 proof(induct r arbitrary: s v1)
   case (ZERO s v1)
-  have "v1 \<in> CV ZERO s" by fact
-  then show "s \<in> ZERO \<rightarrow> v1" unfolding CV_def
-    by (auto elim: CPrf.cases)
+  have "v1 \<in> LV ZERO s" by fact
+  then show "s \<in> ZERO \<rightarrow> v1" unfolding LV_def
+    by (auto elim: Prf.cases)
 next 
   case (ONE s v1)
-  have "v1 \<in> CV ONE s" by fact
-  then show "s \<in> ONE \<rightarrow> v1" unfolding CV_def
-    by(auto elim!: CPrf.cases intro: Posix.intros)
+  have "v1 \<in> LV ONE s" by fact
+  then show "s \<in> ONE \<rightarrow> v1" unfolding LV_def
+    by(auto elim!: Prf.cases intro: Posix.intros)
 next 
   case (CHAR c s v1)
-  have "v1 \<in> CV (CHAR c) s" by fact
-  then show "s \<in> CHAR c \<rightarrow> v1" unfolding CV_def
-    by (auto elim!: CPrf.cases intro: Posix.intros)
+  have "v1 \<in> LV (CHAR c) s" by fact
+  then show "s \<in> CHAR c \<rightarrow> v1" unfolding LV_def
+    by (auto elim!: Prf.cases intro: Posix.intros)
 next
   case (ALT r1 r2 s v1)
-  have IH1: "\<And>s v1. \<lbrakk>v1 \<in> CV r1 s; \<forall>v2 \<in> LV r1 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r1 \<rightarrow> v1" by fact
-  have IH2: "\<And>s v1. \<lbrakk>v1 \<in> CV r2 s; \<forall>v2 \<in> LV r2 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r2 \<rightarrow> v1" by fact
+  have IH1: "\<And>s v1. \<lbrakk>v1 \<in> LV r1 s; \<forall>v2 \<in> LV r1 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r1 \<rightarrow> v1" by fact
+  have IH2: "\<And>s v1. \<lbrakk>v1 \<in> LV r2 s; \<forall>v2 \<in> LV r2 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r2 \<rightarrow> v1" by fact
   have as1: "\<forall>v2\<in>LV (ALT r1 r2) s. \<not> v2 :\<sqsubset>val v1" by fact
-  have as2: "v1 \<in> CV (ALT r1 r2) s" by fact
+  have as2: "v1 \<in> LV (ALT r1 r2) s" by fact
   then consider 
      (Left) v1' where
         "v1 = Left v1'" "s = flat v1'"
-        "v1' \<in> CV r1 s"
+        "v1' \<in> LV r1 s"
   |  (Right) v1' where
         "v1 = Right v1'" "s = flat v1'"
-        "v1' \<in> CV r2 s"
-  unfolding CV_def by (auto elim: CPrf.cases)
+        "v1' \<in> LV r2 s"
+  unfolding LV_def by (auto elim: Prf.cases)
   then show "s \<in> ALT r1 r2 \<rightarrow> v1"
    proof (cases)
      case (Left v1')
-     have "v1' \<in> CV r1 s" using as2
-       unfolding CV_def Left by (auto elim: CPrf.cases)
+     have "v1' \<in> LV r1 s" using as2
+       unfolding LV_def Left by (auto elim: Prf.cases)
      moreover
      have "\<forall>v2 \<in> LV r1 s. \<not> v2 :\<sqsubset>val v1'" using as1
        unfolding LV_def Left using Prf.intros(2) PosOrd_Left_eq by force  
@@ -828,8 +851,8 @@
      then show "s \<in> ALT r1 r2 \<rightarrow> v1" using Left by simp
    next
      case (Right v1')
-     have "v1' \<in> CV r2 s" using as2
-       unfolding CV_def Right by (auto elim: CPrf.cases)
+     have "v1' \<in> LV r2 s" using as2
+       unfolding LV_def Right by (auto elim: Prf.cases)
      moreover
      have "\<forall>v2 \<in> LV r2 s. \<not> v2 :\<sqsubset>val v1'" using as1
        unfolding LV_def Right using Prf.intros(3) PosOrd_RightI by force   
@@ -841,7 +864,8 @@
          then have "Left v' \<in>  LV (ALT r1 r2) s" 
             unfolding LV_def by (auto intro: Prf.intros)
          with as1 have "\<not> (Left v' :\<sqsubset>val Right v1') \<and> (flat v' = s)" 
-            unfolding LV_def Right by (auto)
+            unfolding LV_def Right 
+            by (auto)
          then have False using PosOrd_Left_Right Right by blast  
        }
      then have "s \<notin> L r1" by rule 
@@ -850,21 +874,21 @@
   qed
 next 
   case (SEQ r1 r2 s v1)
-  have IH1: "\<And>s v1. \<lbrakk>v1 \<in> CV r1 s; \<forall>v2 \<in> LV r1 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r1 \<rightarrow> v1" by fact
-  have IH2: "\<And>s v1. \<lbrakk>v1 \<in> CV r2 s; \<forall>v2 \<in> LV r2 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r2 \<rightarrow> v1" by fact
+  have IH1: "\<And>s v1. \<lbrakk>v1 \<in> LV r1 s; \<forall>v2 \<in> LV r1 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r1 \<rightarrow> v1" by fact
+  have IH2: "\<And>s v1. \<lbrakk>v1 \<in> LV r2 s; \<forall>v2 \<in> LV r2 s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r2 \<rightarrow> v1" by fact
   have as1: "\<forall>v2\<in>LV (SEQ r1 r2) s. \<not> v2 :\<sqsubset>val v1" by fact
-  have as2: "v1 \<in> CV (SEQ r1 r2) s" by fact
+  have as2: "v1 \<in> LV (SEQ r1 r2) s" by fact
   then obtain 
     v1a v1b where eqs:
         "v1 = Seq v1a v1b" "s = flat v1a @ flat v1b"
-        "v1a \<in> CV r1 (flat v1a)" "v1b \<in> CV r2 (flat v1b)" 
-  unfolding CV_def by(auto elim: CPrf.cases)
+        "v1a \<in> LV r1 (flat v1a)" "v1b \<in> LV r2 (flat v1b)" 
+  unfolding LV_def by(auto elim: Prf.cases)
   have "\<forall>v2 \<in> LV r1 (flat v1a). \<not> v2 :\<sqsubset>val v1a"
     proof
       fix v2
       assume "v2 \<in> LV r1 (flat v1a)"
       with eqs(2,4) have "Seq v2 v1b \<in> LV (SEQ r1 r2) s"
-         by (simp add: CV_def LV_def Prf.intros(1) Prf_CPrf)
+         by (simp add: LV_def Prf.intros(1))
       with as1 have "\<not> Seq v2 v1b :\<sqsubset>val Seq v1a v1b \<and> flat (Seq v2 v1b) = flat (Seq v1a v1b)" 
          using eqs by (simp add: LV_def) 
       then show "\<not> v2 :\<sqsubset>val v1a"
@@ -877,7 +901,7 @@
       fix v2
       assume "v2 \<in> LV r2 (flat v1b)"
       with eqs(2,3,4) have "Seq v1a v2 \<in> LV (SEQ r1 r2) s"
-         by (simp add: CV_def LV_def Prf.intros Prf_CPrf)
+         by (simp add: LV_def Prf.intros)
       with as1 have "\<not> Seq v1a v2 :\<sqsubset>val Seq v1a v1b \<and> flat v2 = flat v1b" 
          using eqs by (simp add: LV_def) 
       then show "\<not> v2 :\<sqsubset>val v1b"
@@ -889,10 +913,10 @@
   proof
      assume "\<exists>s3 s4. s3 \<noteq> [] \<and> s3 @ s4 = flat v1b \<and> flat v1a @ s3 \<in> L r1 \<and> s4 \<in> L r2"
      then obtain s3 s4 where q1: "s3 \<noteq> [] \<and> s3 @ s4 = flat v1b \<and> flat v1a @ s3 \<in> L r1 \<and> s4 \<in> L r2" by blast
-     then obtain vA vB where q2: "flat vA = flat v1a @ s3" "\<turnstile> vA : r1" "flat vB = s4" "\<turnstile> vB : r2"
+     then obtain vA vB where q2: "flat vA = flat v1a @ s3" "\<Turnstile> vA : r1" "flat vB = s4" "\<Turnstile> vB : r2"
         using L_flat_Prf2 by blast
      then have "Seq vA vB \<in> LV (SEQ r1 r2) s" unfolding eqs using q1
-       by (auto simp add: LV_def intro: Prf.intros)
+       by (auto simp add: LV_def intro!: Prf.intros)
      with as1 have "\<not> Seq vA vB :\<sqsubset>val Seq v1a v1b" unfolding eqs by auto
      then have "\<not> vA :\<sqsubset>val v1a \<and> length (flat vA) > length (flat v1a)" using q1 q2 PosOrd_SeqI1 by auto 
      then show "False"
@@ -903,14 +927,14 @@
     by (rule Posix.intros)
 next
    case (STAR r s v1)
-   have IH: "\<And>s v1. \<lbrakk>v1 \<in> CV r s; \<forall>v2\<in>LV r s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r \<rightarrow> v1" by fact
+   have IH: "\<And>s v1. \<lbrakk>v1 \<in> LV r s; \<forall>v2\<in>LV r s. \<not> v2 :\<sqsubset>val v1\<rbrakk> \<Longrightarrow> s \<in> r \<rightarrow> v1" by fact
    have as1: "\<forall>v2\<in>LV (STAR r) s. \<not> v2 :\<sqsubset>val v1" by fact
-   have as2: "v1 \<in> CV (STAR r) s" by fact
+   have as2: "v1 \<in> LV (STAR r) s" by fact
    then obtain 
     vs where eqs:
         "v1 = Stars vs" "s = flat (Stars vs)"
-        "\<forall>v \<in> set vs. v \<in> CV r (flat v)"
-        unfolding CV_def by (auto elim: CPrf.cases)
+        "\<forall>v \<in> set vs. v \<in> LV r (flat v)"
+        unfolding LV_def by (auto elim: Prf.cases)
    have "\<forall>v\<in>set vs. flat v \<in> r \<rightarrow> v \<and> flat v \<noteq> []" 
      proof 
         fix v
@@ -926,9 +950,9 @@
              assume "v2 \<in> LV r (flat v)"
              then have "Stars (pre @ [v2] @ post) \<in> LV (STAR r) s" 
                  using as2 unfolding e eqs
-                 apply(auto simp add: CV_def LV_def intro!: Prf.intros)[1]
-                 using CPrf_Stars_appendE Prf_CPrf Prf_elims(6) list.set_intros apply blast
-                 by (metis CPrf_Stars_appendE Prf_CPrf Prf_elims(6) list.set_intros(2) val.inject(5))
+                 apply(auto simp add: LV_def intro!: Prf.intros elim: Prf_elims dest: Prf_Stars_appendE)
+                 apply(auto dest!: Prf_Stars_appendE elim: Prf.cases)
+                 done
              then have  "\<not> Stars (pre @ [v2] @ post) :\<sqsubset>val Stars (pre @ [v] @ post)"
                 using q by simp     
              with w show "False"
@@ -936,25 +960,18 @@
                 PosOrd_StarsI PosOrd_Stars_appendI by auto
           qed     
         with IH
-        show "flat v \<in> r \<rightarrow> v \<and> flat v \<noteq> []" using a as2 unfolding eqs CV_def
-        by (auto elim: CPrf.cases)
+        show "flat v \<in> r \<rightarrow> v \<and> flat v \<noteq> []" using a as2 unfolding eqs LV_def
+        by (auto elim: Prf.cases)
      qed
    moreover
    have "\<not> (\<exists>vs2\<in>LV (STAR r) (flat (Stars vs)). vs2 :\<sqsubset>val Stars vs)" 
      proof 
        assume "\<exists>vs2 \<in> LV (STAR r) (flat (Stars vs)). vs2 :\<sqsubset>val Stars vs"
-       then obtain vs2 where "\<turnstile> Stars vs2 : STAR r" "flat (Stars vs2) = flat (Stars vs)"
+       then obtain vs2 where "\<Turnstile> Stars vs2 : STAR r" "flat (Stars vs2) = flat (Stars vs)"
                              "Stars vs2 :\<sqsubset>val Stars vs" 
-         unfolding LV_def
-         apply(auto)
-         apply(erule Prf.cases)
-         apply(auto intro: Prf.intros)
-         done
+         unfolding LV_def by (force elim: Prf_elims intro: Prf.intros)
        then show "False" using as1 unfolding eqs
-         apply -
-         apply(drule_tac x="Stars vs2" in bspec)
-         apply(auto simp add: LV_def)
-         done
+         by (auto simp add: LV_def)
      qed
    ultimately have "flat (Stars vs) \<in> STAR r \<rightarrow> Stars vs"
      thm PosOrd_Posix_Stars
@@ -962,6 +979,55 @@
    then show "s \<in> STAR r \<rightarrow> v1" unfolding eqs .
 qed
 
+lemma Least_existence:
+  assumes "LV r s \<noteq> {}"
+  shows " \<exists>vmin \<in> LV r s. \<forall>v \<in> LV r s. vmin :\<sqsubseteq>val v"
+proof -
+  from assms
+  obtain vposix where "s \<in> r \<rightarrow> vposix"
+  unfolding LV_def 
+  using L_flat_Prf1 lexer_correct_Some by blast
+  then have "\<forall>v \<in> LV r s. vposix :\<sqsubseteq>val v"
+    by (simp add: Posix_PosOrd)
+  then show "\<exists>vmin \<in> LV r s. \<forall>v \<in> LV r s. vmin :\<sqsubseteq>val v"
+    using Posix_LV \<open>s \<in> r \<rightarrow> vposix\<close> by blast
+qed 
+
+lemma Least_existence1:
+  assumes "LV r s \<noteq> {}"
+  shows " \<exists>!vmin \<in> LV r s. \<forall>v \<in> (LV r s \<union> {v'. flat v' \<sqsubset>spre s}). vmin :\<sqsubseteq>val v"
+using Least_existence[OF assms] assms
+apply -
+apply(erule bexE)
+apply(rule_tac a="vmin" in ex1I)
+apply(auto)[1]
+apply (metis PosOrd_Posix PosOrd_ex_eq2 PosOrd_spreI PosOrdeq_antisym Posix1(2))
+apply(auto)[1]
+apply(simp add: PosOrdeq_antisym)
+done
+
+lemma
+  shows "partial_order_on UNIV {(v1, v2). v1 :\<sqsubseteq>val v2}"
+apply(simp add: partial_order_on_def)
+apply(simp add: preorder_on_def refl_on_def)
+apply(simp add: PosOrdeq_refl)
+apply(auto)
+apply(rule transI)
+apply(auto intro: PosOrdeq_trans)[1]
+apply(rule antisymI)
+apply(simp add: PosOrdeq_antisym)
+done
+
+lemma
+ "wf {(v1, v2). v1 :\<sqsubset>val v2 \<and> v1 \<in> LV r s \<and> v2 \<in> LV r s}"
+apply(rule finite_acyclic_wf)
+prefer 2
+apply(simp add: acyclic_def)
+apply(induct_tac rule: trancl.induct)
+apply(auto)[1]
+oops
+
+
 unused_thms
 
 end
\ No newline at end of file
--- a/thys/Spec.thy	Fri Aug 11 20:29:01 2017 +0100
+++ b/thys/Spec.thy	Fri Aug 18 14:51:29 2017 +0100
@@ -176,35 +176,6 @@
 
 
 
-section {* Lemmas about ders *}
-
-(* not really needed *)
-
-lemma ders_ZERO:
-  shows "ders s (ZERO) = ZERO"
-apply(induct s)
-apply(simp_all)
-done
-
-lemma ders_ONE:
-  shows "ders s (ONE) = (if s = [] then ONE else ZERO)"
-apply(induct s)
-apply(simp_all add: ders_ZERO)
-done
-
-lemma ders_CHAR:
-  shows "ders s (CHAR c) = 
-           (if s = [c] then ONE else 
-           (if s = [] then (CHAR c) else ZERO))"
-apply(induct s)
-apply(simp_all add: ders_ZERO ders_ONE)
-done
-
-lemma  ders_ALT:
-  shows "ders s (ALT r1 r2) = ALT (ders s r1) (ders s r2)"
-by (induct s arbitrary: r1 r2)(simp_all)
-
-
 section {* Values *}
 
 datatype val = 
@@ -236,109 +207,33 @@
  "flat (Stars vs) = flats vs"
 by (induct vs) (auto)
 
-
-section {* Relation between values and regular expressions *}
-
-inductive 
-  Prf :: "val \<Rightarrow> rexp \<Rightarrow> bool" ("\<turnstile> _ : _" [100, 100] 100)
-where
- "\<lbrakk>\<turnstile> v1 : r1; \<turnstile> v2 : r2\<rbrakk> \<Longrightarrow> \<turnstile> Seq v1 v2 : SEQ r1 r2"
-| "\<turnstile> v1 : r1 \<Longrightarrow> \<turnstile> Left v1 : ALT r1 r2"
-| "\<turnstile> v2 : r2 \<Longrightarrow> \<turnstile> Right v2 : ALT r1 r2"
-| "\<turnstile> Void : ONE"
-| "\<turnstile> Char c : CHAR c"
-| "\<forall>v \<in> set vs. \<turnstile> v : r \<Longrightarrow> \<turnstile> Stars vs : STAR r"
-
-inductive_cases Prf_elims:
-  "\<turnstile> v : ZERO"
-  "\<turnstile> v : SEQ r1 r2"
-  "\<turnstile> v : ALT r1 r2"
-  "\<turnstile> v : ONE"
-  "\<turnstile> v : CHAR c"
-  "\<turnstile> vs : STAR r"
-
 lemma Star_concat:
   assumes "\<forall>s \<in> set ss. s \<in> A"  
   shows "concat ss \<in> A\<star>"
 using assms by (induct ss) (auto)
 
-lemma Star_string:
+lemma Star_cstring:
   assumes "s \<in> A\<star>"
-  shows "\<exists>ss. concat ss = s \<and> (\<forall>s \<in> set ss. s \<in> A)"
+  shows "\<exists>ss. concat ss = s \<and> (\<forall>s \<in> set ss. s \<in> A \<and> s \<noteq> [])"
 using assms
 apply(induct rule: Star.induct)
-apply(auto)
+apply(auto)[1]
 apply(rule_tac x="[]" in exI)
 apply(simp)
+apply(erule exE)
+apply(clarify)
+apply(case_tac "s1 = []")
+apply(rule_tac x="ss" in exI)
+apply(simp)
 apply(rule_tac x="s1#ss" in exI)
 apply(simp)
 done
 
-lemma Star_val:
-  assumes "\<forall>s\<in>set ss. \<exists>v. s = flat v \<and> \<turnstile> v : r"
-  shows "\<exists>vs. flats vs = concat ss \<and> (\<forall>v\<in>set vs. \<turnstile> v : r)"
-using assms
-apply(induct ss)
-apply(auto)
-apply(rule_tac x="[]" in exI)
-apply(simp)
-apply(rule_tac x="v#vs" in exI)
-apply(simp)
-done
 
-lemma Prf_Stars_append:
-  assumes "\<turnstile> Stars vs1 : STAR r" "\<turnstile> Stars vs2 : STAR r"
-  shows "\<turnstile> Stars (vs1 @ vs2) : STAR r"
-using assms
-by (auto intro!: Prf.intros elim!: Prf_elims)
-
-lemma Prf_flat_L:
-  assumes "\<turnstile> v : r" 
-  shows "flat v \<in> L r"
-using assms
-by (induct v r rule: Prf.induct)
-   (auto simp add: Sequ_def Star_concat)
-
-
-lemma L_flat_Prf1:
-  assumes "\<turnstile> v : r" 
-  shows "flat v \<in> L r"
-using assms
-by (induct) (auto simp add: Sequ_def Star_concat)
-
-lemma L_flat_Prf2:
-  assumes "s \<in> L r" 
-  shows "\<exists>v. \<turnstile> v : r \<and> flat v = s"
-using assms
-proof(induct r arbitrary: s)
-  case (STAR r s)
-  have IH: "\<And>s. s \<in> L r \<Longrightarrow> \<exists>v. \<turnstile> v : r \<and> flat v = s" by fact
-  have "s \<in> L (STAR r)" by fact
-  then obtain ss where "concat ss = s" "\<forall>s \<in> set ss. s \<in> L r"
-  using Star_string by auto
-  then obtain vs where "flats vs = s" "\<forall>v\<in>set vs. \<turnstile> v : r"
-  using IH Star_val by blast
-  then show "\<exists>v. \<turnstile> v : STAR r \<and> flat v = s"
-  using Prf.intros(6) flat_Stars by blast
-next 
-  case (SEQ r1 r2 s)
-  then show "\<exists>v. \<turnstile> v : SEQ r1 r2 \<and> flat v = s"
-  unfolding Sequ_def L.simps by (fastforce intro: Prf.intros)
-next
-  case (ALT r1 r2 s)
-  then show "\<exists>v. \<turnstile> v : ALT r1 r2 \<and> flat v = s"
-  unfolding L.simps by (fastforce intro: Prf.intros)
-qed (auto intro: Prf.intros)
-
-lemma L_flat_Prf:
-  shows "L(r) = {flat v | v. \<turnstile> v : r}"
-using L_flat_Prf1 L_flat_Prf2 by blast
-
-
-section {* Canonical Values *}
+section {* Lexical Values *}
 
 inductive 
-  CPrf :: "val \<Rightarrow> rexp \<Rightarrow> bool" ("\<Turnstile> _ : _" [100, 100] 100)
+  Prf :: "val \<Rightarrow> rexp \<Rightarrow> bool" ("\<Turnstile> _ : _" [100, 100] 100)
 where
  "\<lbrakk>\<Turnstile> v1 : r1; \<Turnstile> v2 : r2\<rbrakk> \<Longrightarrow> \<Turnstile>  Seq v1 v2 : SEQ r1 r2"
 | "\<Turnstile> v1 : r1 \<Longrightarrow> \<Turnstile> Left v1 : ALT r1 r2"
@@ -347,34 +242,92 @@
 | "\<Turnstile> Char c : CHAR c"
 | "\<forall>v \<in> set vs. \<Turnstile> v : r \<and> flat v \<noteq> [] \<Longrightarrow> \<Turnstile> Stars vs : STAR r"
 
-lemma Prf_CPrf:
-  assumes "\<Turnstile> v : r"
-  shows "\<turnstile> v : r"
-using assms
-by (induct)(auto intro: Prf.intros)
+inductive_cases Prf_elims:
+  "\<Turnstile> v : ZERO"
+  "\<Turnstile> v : SEQ r1 r2"
+  "\<Turnstile> v : ALT r1 r2"
+  "\<Turnstile> v : ONE"
+  "\<Turnstile> v : CHAR c"
+  "\<Turnstile> vs : STAR r"
 
-lemma CPrf_Stars_appendE:
+lemma Prf_Stars_appendE:
   assumes "\<Turnstile> Stars (vs1 @ vs2) : STAR r"
   shows "\<Turnstile> Stars vs1 : STAR r \<and> \<Turnstile> Stars vs2 : STAR r" 
 using assms
-apply(erule_tac CPrf.cases)
-apply(auto intro: CPrf.intros)
+by (auto intro: Prf.intros elim!: Prf_elims)
+
+
+lemma Star_cval:
+  assumes "\<forall>s\<in>set ss. \<exists>v. s = flat v \<and> \<Turnstile> v : r"
+  shows "\<exists>vs. flats vs = concat ss \<and> (\<forall>v\<in>set vs. \<Turnstile> v : r \<and> flat v \<noteq> [])"
+using assms
+apply(induct ss)
+apply(auto)
+apply(rule_tac x="[]" in exI)
+apply(simp)
+apply(case_tac "flat v = []")
+apply(rule_tac x="vs" in exI)
+apply(simp)
+apply(rule_tac x="v#vs" in exI)
+apply(simp)
 done
 
 
-section {* Sets of Lexical and Canonical Values *}
+lemma L_flat_Prf1:
+  assumes "\<Turnstile> v : r" 
+  shows "flat v \<in> L r"
+using assms
+by (induct) (auto simp add: Sequ_def Star_concat)
 
-definition 
-  LV :: "rexp \<Rightarrow> string \<Rightarrow> val set"
-where "LV r s \<equiv> {v.  \<turnstile> v : r \<and> flat v = s}"
+lemma L_flat_Prf2:
+  assumes "s \<in> L r" 
+  shows "\<exists>v. \<Turnstile> v : r \<and> flat v = s"
+using assms
+proof(induct r arbitrary: s)
+  case (STAR r s)
+  have IH: "\<And>s. s \<in> L r \<Longrightarrow> \<exists>v. \<Turnstile> v : r \<and> flat v = s" by fact
+  have "s \<in> L (STAR r)" by fact
+  then obtain ss where "concat ss = s" "\<forall>s \<in> set ss. s \<in> L r \<and> s \<noteq> []"
+  using Star_cstring by auto  
+  then obtain vs where "flats vs = s" "\<forall>v\<in>set vs. \<Turnstile> v : r \<and> flat v \<noteq> []"
+  using IH Star_cval by metis 
+  then show "\<exists>v. \<Turnstile> v : STAR r \<and> flat v = s"
+  using Prf.intros(6) flat_Stars by blast
+next 
+  case (SEQ r1 r2 s)
+  then show "\<exists>v. \<Turnstile> v : SEQ r1 r2 \<and> flat v = s"
+  unfolding Sequ_def L.simps by (fastforce intro: Prf.intros)
+next
+  case (ALT r1 r2 s)
+  then show "\<exists>v. \<Turnstile> v : ALT r1 r2 \<and> flat v = s"
+  unfolding L.simps by (fastforce intro: Prf.intros)
+qed (auto intro: Prf.intros)
+
+
+lemma L_flat_Prf:
+  shows "L(r) = {flat v | v. \<Turnstile> v : r}"
+using L_flat_Prf1 L_flat_Prf2 by blast
+
+
+
+section {* Sets of Lexical Values *}
+
+text {*
+  Shows that lexical values are finite for a given regex and string.
+*}
 
 definition
-  CV :: "rexp \<Rightarrow> string \<Rightarrow> val set"
-where  "CV r s \<equiv> {v. \<Turnstile> v : r \<and> flat v = s}"
+  LV :: "rexp \<Rightarrow> string \<Rightarrow> val set"
+where  "LV r s \<equiv> {v. \<Turnstile> v : r \<and> flat v = s}"
 
-lemma LV_CV_subset:
-  shows "CV r s \<subseteq> LV r s"
-unfolding CV_def LV_def by(auto simp add: Prf_CPrf)
+lemma LV_simps:
+  shows "LV ZERO s = {}"
+  and   "LV ONE s = (if s = [] then {Void} else {})"
+  and   "LV (CHAR c) s = (if s = [c] then {Char c} else {})"
+  and   "LV (ALT r1 r2) s = Left ` LV r1 s \<union> Right ` LV r2 s"
+unfolding LV_def
+by (auto intro: Prf.intros elim: Prf.cases)
+
 
 abbreviation
   "Prefixes s \<equiv> {s'. prefixeq s' s}"
@@ -389,13 +342,6 @@
   shows "Suffixes (c # s) = Suffixes s \<union> {c # s}"
 by (auto simp add: suffixeq_def Cons_eq_append_conv)
 
-lemma CV_simps:
-  shows "CV ZERO s = {}"
-  and   "CV ONE s = (if s = [] then {Void} else {})"
-  and   "CV (CHAR c) s = (if s = [c] then {Char c} else {})"
-  and   "CV (ALT r1 r2) s = Left ` CV r1 s \<union> Right ` CV r2 s"
-unfolding CV_def
-by (auto intro: CPrf.intros elim: CPrf.cases)
 
 lemma finite_Suffixes: 
   shows "finite (Suffixes s)"
@@ -423,34 +369,17 @@
   ultimately show "finite (Prefixes s)" by simp
 qed
 
-lemma CV_SEQ_subset:
-  "CV (SEQ r1 r2) s \<subseteq> (\<lambda>(v1,v2). Seq v1 v2) ` ((\<Union>s' \<in> Prefixes s. CV r1 s') \<times> (\<Union>s' \<in> Suffixes s. CV r2 s'))"
-unfolding image_def CV_def prefixeq_def suffixeq_def
-by (auto elim: CPrf.cases)
-
-lemma CV_STAR_subset:
-  "CV (STAR r) s \<subseteq> {Stars []} \<union>
-      (\<lambda>(v,vs). Stars (v#vs)) ` ((\<Union>s' \<in> Prefixes s. CV r s') \<times> (\<Union>s2 \<in> SSuffixes s. Stars -` (CV (STAR r) s2)))"
-unfolding image_def CV_def prefixeq_def suffix_def
-apply(auto)
-apply(erule CPrf.cases)
-apply(auto)
-apply(case_tac vs)
-apply(auto intro: CPrf.intros)
-done
-
-
-lemma CV_STAR_finite:
-  assumes "\<forall>s. finite (CV r s)"
-  shows "finite (CV (STAR r) s)"
+lemma LV_STAR_finite:
+  assumes "\<forall>s. finite (LV r s)"
+  shows "finite (LV (STAR r) s)"
 proof(induct s rule: length_induct)
   fix s::"char list"
-  assume "\<forall>s'. length s' < length s \<longrightarrow> finite (CV (STAR r) s')"
-  then have IH: "\<forall>s' \<in> SSuffixes s. finite (CV (STAR r) s')"
+  assume "\<forall>s'. length s' < length s \<longrightarrow> finite (LV (STAR r) s')"
+  then have IH: "\<forall>s' \<in> SSuffixes s. finite (LV (STAR r) s')"
     by (auto simp add: suffix_def) 
   def f \<equiv> "\<lambda>(v, vs). Stars (v # vs)"
-  def S1 \<equiv> "\<Union>s' \<in> Prefixes s. CV r s'"
-  def S2 \<equiv> "\<Union>s2 \<in> SSuffixes s. Stars -` (CV (STAR r) s2)"
+  def S1 \<equiv> "\<Union>s' \<in> Prefixes s. LV r s'"
+  def S2 \<equiv> "\<Union>s2 \<in> SSuffixes s. Stars -` (LV (STAR r) s2)"
   have "finite S1" using assms
     unfolding S1_def by (simp_all add: finite_Prefixes)
   moreover 
@@ -459,44 +388,53 @@
   ultimately 
   have "finite ({Stars []} \<union> f ` (S1 \<times> S2))" by simp
   moreover 
-  have "CV (STAR r) s \<subseteq> {Stars []} \<union> f ` (S1 \<times> S2)" unfolding S1_def S2_def f_def
-     by (rule CV_STAR_subset)
+  have "LV (STAR r) s \<subseteq> {Stars []} \<union> f ` (S1 \<times> S2)" 
+  unfolding S1_def S2_def f_def
+  unfolding LV_def image_def prefixeq_def suffix_def
+  apply(auto elim: Prf_elims)
+  apply(erule Prf_elims)
+  apply(auto)
+  apply(case_tac vs)
+  apply(auto intro: Prf.intros)
+  done  
   ultimately
-  show "finite (CV (STAR r) s)" by (simp add: finite_subset)
+  show "finite (LV (STAR r) s)" by (simp add: finite_subset)
 qed  
     
 
-lemma CV_finite:
-  shows "finite (CV r s)"
+lemma LV_finite:
+  shows "finite (LV r s)"
 proof(induct r arbitrary: s)
   case (ZERO s) 
-  show "finite (CV ZERO s)" by (simp add: CV_simps)
+  show "finite (LV ZERO s)" by (simp add: LV_simps)
 next
   case (ONE s)
-  show "finite (CV ONE s)" by (simp add: CV_simps)
+  show "finite (LV ONE s)" by (simp add: LV_simps)
 next
   case (CHAR c s)
-  show "finite (CV (CHAR c) s)" by (simp add: CV_simps)
+  show "finite (LV (CHAR c) s)" by (simp add: LV_simps)
 next 
   case (ALT r1 r2 s)
-  then show "finite (CV (ALT r1 r2) s)" by (simp add: CV_simps)
+  then show "finite (LV (ALT r1 r2) s)" by (simp add: LV_simps)
 next 
   case (SEQ r1 r2 s)
   def f \<equiv> "\<lambda>(v1, v2). Seq v1 v2"
-  def S1 \<equiv> "\<Union>s' \<in> Prefixes s. CV r1 s'"
-  def S2 \<equiv> "\<Union>s' \<in> Suffixes s. CV r2 s'"
-  have IHs: "\<And>s. finite (CV r1 s)" "\<And>s. finite (CV r2 s)" by fact+
+  def S1 \<equiv> "\<Union>s' \<in> Prefixes s. LV r1 s'"
+  def S2 \<equiv> "\<Union>s' \<in> Suffixes s. LV r2 s'"
+  have IHs: "\<And>s. finite (LV r1 s)" "\<And>s. finite (LV r2 s)" by fact+
   then have "finite S1" "finite S2" unfolding S1_def S2_def
     by (simp_all add: finite_Prefixes finite_Suffixes)
   moreover
-  have "CV (SEQ r1 r2) s \<subseteq> f ` (S1 \<times> S2)"
-    unfolding f_def S1_def S2_def by (auto simp add: CV_SEQ_subset)
+  have "LV (SEQ r1 r2) s \<subseteq> f ` (S1 \<times> S2)"
+    unfolding f_def S1_def S2_def 
+    unfolding LV_def image_def prefixeq_def suffixeq_def
+    by (auto elim: Prf.cases)
   ultimately 
-  show "finite (CV (SEQ r1 r2) s)"
+  show "finite (LV (SEQ r1 r2) s)"
     by (simp add: finite_subset)
 next
   case (STAR r s)
-  then show "finite (CV (STAR r) s)" by (simp add: CV_STAR_finite)
+  then show "finite (LV (STAR r) s)" by (simp add: LV_STAR_finite)
 qed
 
 
@@ -533,14 +471,6 @@
 by (induct s r v rule: Posix.induct)
    (auto simp add: Sequ_def)
 
-lemma Posix_Prf:
-  assumes "s \<in> r \<rightarrow> v"
-  shows "\<turnstile> v : r"
-using assms
-apply(induct s r v rule: Posix.induct)
-apply(auto intro!: Prf.intros elim!: Prf_elims)
-done
-
 text {*
   Our Posix definition determines a unique value.
 *}
@@ -616,30 +546,31 @@
   Our POSIX value is a canonical value.
 *}
 
-lemma Posix_CV:
+lemma Posix_LV:
   assumes "s \<in> r \<rightarrow> v"
-  shows "v \<in> CV r s"
+  shows "v \<in> LV r s"
 using assms
 apply(induct rule: Posix.induct)
-apply(auto simp add: CV_def intro: CPrf.intros elim: CPrf.cases)
+apply(auto simp add: LV_def intro: Prf.intros elim: Prf.cases)
 apply(rotate_tac 5)
-apply(erule CPrf.cases)
+apply(erule Prf.cases)
 apply(simp_all)
-apply(rule CPrf.intros)
+apply(rule Prf.intros)
 apply(simp_all)
 done
 
+(*
 lemma test2: 
   assumes "\<forall>v \<in> set vs. flat v \<in> r \<rightarrow> v \<and> flat v \<noteq> []"
-  shows "(Stars vs) \<in> CV (STAR r) (flat (Stars vs))" 
+  shows "(Stars vs) \<in> LV (STAR r) (flat (Stars vs))" 
 using assms
 apply(induct vs)
-apply(auto simp add: CV_def)
-apply(rule CPrf.intros)
+apply(auto simp add: LV_def)
+apply(rule Prf.intros)
 apply(simp)
-apply(rule CPrf.intros)
+apply(rule Prf.intros)
 apply(simp_all)
-by (metis (no_types, lifting) CV_def Posix_CV mem_Collect_eq)
-
+by (metis (no_types, lifting) LV_def Posix_LV mem_Collect_eq)
+*)
 
 end
\ No newline at end of file