(* Title: HOL/ex/BinEx.thy
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1998 University of Cambridge
Definition of normal form for proving that binary arithmetic on
normalized operands yields normalized results.
Normal means no leading 0s on positive numbers and no leading 1s on negatives.
*)
BinEx = Main +
consts normal :: bin set
inductive "normal"
intrs
Pls "Pls: normal"
Min "Min: normal"
BIT_F "[| w: normal; w ~= Pls |] ==> w BIT False : normal"
BIT_T "[| w: normal; w ~= Min |] ==> w BIT True : normal"
end