Added constant abs.
(* 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.
*)
header {* The accessible part of a relation *};
theory Acc = WF + Inductive:;
consts
acc :: "('a * 'a)set => 'a set" -- {* accessible part *};
inductive "acc r"
intrs
accI [rulify_prems]:
"ALL y. (y, x) : r --> y : acc r ==> x : acc r"
syntax
termi :: "('a * 'a)set => 'a set"
translations
"termi r" == "acc(r^-1)"
end