src/HOL/Lambda/ParRed.thy

Simplified primrec definitions.

(*  Title:      HOL/Lambda/ParRed.thy
    ID:         $Id$
    Author:     Tobias Nipkow
    Copyright   1995 TU Muenchen

Parallel reduction and a complete developments function "cd".
*)

ParRed = Lambda + Commutation +

consts  par_beta :: "(db * db) set"

syntax  "=>" :: [db,db] => bool (infixl 50)

translations
  "s => t" == "(s,t) : par_beta"

inductive par_beta
  intrs
    var   "Var n => Var n"
    abs   "s => t ==> Fun s => Fun t"
    app   "[| s => s'; t => t' |] ==> s @ t => s' @ t'"
    beta  "[| s => s'; t => t' |] ==> (Fun s) @ t => s'[t'/0]"

consts
  cd  :: db => db
  deFun :: db => db

primrec cd db
  "cd(Var n) = Var n"
  "cd(s @ t) = (case s of
            Var n => s @ (cd t) |
            s1 @ s2 => (cd s) @ (cd t) |
            Fun u => deFun(cd s)[cd t/0])"
  "cd(Fun s) = Fun(cd s)"

primrec deFun db
  "deFun(Var n) = Var n"
  "deFun(s @ t) = s @ t"
  "deFun(Fun s) = s"
end