Paper/Paper.thy
changeset 160 ea2e5acbfe4a
parent 159 990c12ab1562
child 162 e93760534354
equal deleted inserted replaced
159:990c12ab1562 160:ea2e5acbfe4a
   511   \begin{equation}\label{inv2}
   511   \begin{equation}\label{inv2}
   512   @{text "X\<^isub>1 = \<calL>(Y\<^isub>1\<^isub>1, CHAR c\<^isub>1\<^isub>1) \<union> \<dots> \<union> \<calL>(Y\<^isub>1\<^isub>p, CHAR c\<^isub>1\<^isub>p) \<union> \<calL>(\<lambda>(EMPTY))"}.
   512   @{text "X\<^isub>1 = \<calL>(Y\<^isub>1\<^isub>1, CHAR c\<^isub>1\<^isub>1) \<union> \<dots> \<union> \<calL>(Y\<^isub>1\<^isub>p, CHAR c\<^isub>1\<^isub>p) \<union> \<calL>(\<lambda>(EMPTY))"}.
   513   \end{equation}
   513   \end{equation}
   514 
   514 
   515   \noindent
   515   \noindent
   516   The reason for adding the @{text \<lambda>}-marker to our initial equational system is 
   516   holds. The reason for adding the @{text \<lambda>}-marker to our initial equational system is 
   517   to obtain this equation: it only holds with the marker, since none of 
   517   to obtain this equation: it only holds with the marker, since none of 
   518   the other terms contain the empty string. The point of the initial equational system is
   518   the other terms contain the empty string. The point of the initial equational system is
   519   that solving it means we will be able to extract a regular expression for every equivalence class. 
   519   that solving it means we will be able to extract a regular expression for every equivalence class. 
   520 
   520 
   521   Our representation for the equations in Isabelle/HOL are pairs,
   521   Our representation for the equations in Isabelle/HOL are pairs,
   719   \end{tabular}
   719   \end{tabular}
   720   \end{center}
   720   \end{center}
   721  
   721  
   722   \noindent
   722   \noindent
   723   The first two ensure that the equational system is always finite (number of equations
   723   The first two ensure that the equational system is always finite (number of equations
   724   and number of terms in each equation); the second makes sure the `meaning' of the 
   724   and number of terms in each equation); the third makes sure the `meaning' of the 
   725   equations is preserved under our transformations. The other properties are a bit more
   725   equations is preserved under our transformations. The other properties are a bit more
   726   technical, but are needed to get our proof through. Distinctness states that every
   726   technical, but are needed to get our proof through. Distinctness states that every
   727   equation in the system is distinct. @{text Ardenable} ensures that we can always
   727   equation in the system is distinct. @{text Ardenable} ensures that we can always
   728   apply the @{text Arden} operation. 
   728   apply the @{text Arden} operation. 
   729   The last property states that every @{text rhs} can only contain equivalence classes
   729   The last property states that every @{text rhs} can only contain equivalence classes
   873 
   873 
   874 section {* Myhill-Nerode, Second Part *}
   874 section {* Myhill-Nerode, Second Part *}
   875 
   875 
   876 text {*
   876 text {*
   877   We will prove in this section the second part of the Myhill-Nerode
   877   We will prove in this section the second part of the Myhill-Nerode
   878   theorem. It can be formulated in our setting as follows.
   878   theorem. It can be formulated in our setting as follows:
   879 
   879 
   880   \begin{theorem}
   880   \begin{theorem}
   881   Given @{text "r"} is a regular expression, then @{thm Myhill_Nerode2}.
   881   Given @{text "r"} is a regular expression, then @{thm Myhill_Nerode2}.
   882   \end{theorem}  
   882   \end{theorem}  
   883 
   883