src/HOL/Induct/Acc.thy
author berghofe
Fri, 24 Jul 1998 13:39:47 +0200
changeset 5191 8ceaa19f7717
parent 5102 8c782c25a11e
child 5273 70f478d55606
permissions -rw-r--r--
Renamed '$' to 'Scons' because of clashes with constants of the same name in theories using datatypes.

(*  Title:      HOL/ex/Acc.thy
    ID:         $Id$
    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
    Copyright   1994  University of Cambridge

Inductive definition of acc(r)

See Ch. Paulin-Mohring, Inductive Definitions in the System Coq.
Research Report 92-49, LIP, ENS Lyon.  Dec 1992.
*)

Acc = WF + Inductive +

constdefs
  pred :: "['b, ('a * 'b)set] => 'a set"        (*Set of predecessors*)
  "pred x r == {y. (y,x):r}"

consts
  acc  :: "('a * 'a)set => 'a set"              (*Accessible part*)

inductive "acc(r)"
  intrs
    pred    "pred a r: Pow(acc(r)) ==> a: acc(r)"
  monos     "[Pow_mono]"

end