author nipkow
Fri, 24 Nov 2000 16:49:27 +0100
changeset 10519 ade64af4c57c
parent 9297 bafe45732b10
child 11024 23bf8d787b04
permissions -rw-r--r--
hide many names from Datatype_Universe.

(*  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"

    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"