src/CCL/trancl.thy
author nipkow
Mon, 06 Aug 2001 13:43:24 +0200
changeset 11464 ddea204de5bc
parent 0 a5a9c433f639
permissions -rw-r--r--
turned translation for 1::nat into def. introduced 1' and replaced most occurrences of 1 by 1'.

(*  Title: 	CCL/trancl.thy
    ID:         $Id$
    Author: 	Martin Coen, Cambridge University Computer Laboratory
    Copyright   1993  University of Cambridge

Transitive closure of a relation
*)

Trancl = CCL +

consts
    trans   :: "i set => o" 	              (*transitivity predicate*)
    id	    :: "i set"
    rtrancl :: "i set => i set"	              ("(_^*)" [100] 100)
    trancl  :: "i set => i set"	              ("(_^+)" [100] 100)  
    O	    :: "[i set,i set] => i set"       (infixr 60)

rules   

trans_def	"trans(r) == (ALL x y z. <x,y>:r --> <y,z>:r --> <x,z>:r)"
comp_def	(*composition of relations*)
		"r O s == {xz. EX x y z. xz = <x,z> & <x,y>:s & <y,z>:r}"
id_def		(*the identity relation*)
		"id == {p. EX x. p = <x,x>}"
rtrancl_def	"r^* == lfp(%s. id Un (r O s))"
trancl_def	"r^+ == r O rtrancl(r)"

end