let b be ordinal number ; for n being natural number st 0 in n holds
<%(n *^ (exp omega ,b))%> is Cantor-normal-form
let n be natural number ; ( 0 in n implies <%(n *^ (exp omega ,b))%> is Cantor-normal-form )
assume A0:
0 in n
; <%(n *^ (exp omega ,b))%> is Cantor-normal-form
set A = <%(n *^ (exp omega ,b))%>;
A1:
( dom <%(n *^ (exp omega ,b))%> = 1 & <%(n *^ (exp omega ,b))%> . 0 = n *^ (exp omega ,b) )
by AFINSQ_1:def 5;
let a, b be ordinal number ; ( a in b & b in dom <%(n *^ (exp omega ,b))%> implies omega -exponent (<%(n *^ (exp omega ,b))%> . b) in omega -exponent (<%(n *^ (exp omega ,b))%> . a) )
assume A2:
a in b
; ( not b in dom <%(n *^ (exp omega ,b))%> or omega -exponent (<%(n *^ (exp omega ,b))%> . b) in omega -exponent (<%(n *^ (exp omega ,b))%> . a) )
assume
b in dom <%(n *^ (exp omega ,b))%>
; omega -exponent (<%(n *^ (exp omega ,b))%> . b) in omega -exponent (<%(n *^ (exp omega ,b))%> . a)
hence
omega -exponent (<%(n *^ (exp omega ,b))%> . b) in omega -exponent (<%(n *^ (exp omega ,b))%> . a)
by A2, A1, TARSKI:def 1, ORDINAL3:18; verum