(* 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 +
consts
pred :: "['b, ('a * 'b)set] => 'a set" (*Set of predecessors*)
acc :: "('a * 'a)set => 'a set" (*Accessible part*)
defs
pred_def "pred(x,r) == {y. <y,x>:r}"
inductive "acc(r)"
intrs
pred "pred(a,r): Pow(acc(r)) ==> a: acc(r)"
monos "[Pow_mono]"
end