let F1, F2 be finite Subset of (Bags n); ( F1 c= Support p & card F1 = i & ( for b, b9 being bag of n st b in F1 & b9 in Support p & b <= b9,T holds
b9 in F1 ) & F2 c= Support p & card F2 = i & ( for b, b9 being bag of n st b in F2 & b9 in Support p & b <= b9,T holds
b9 in F2 ) implies F1 = F2 )
assume that
A22:
F1 c= Support p
and
A23:
card F1 = i
and
A24:
for b, b9 being bag of n st b in F1 & b9 in Support p & b <= b9,T holds
b9 in F1
; ( not F2 c= Support p or not card F2 = i or ex b, b9 being bag of n st
( b in F2 & b9 in Support p & b <= b9,T & not b9 in F2 ) or F1 = F2 )
assume that
A25:
F2 c= Support p
and
A26:
card F2 = i
and
A27:
for b, b9 being bag of n st b in F2 & b9 in Support p & b <= b9,T holds
b9 in F2
; F1 = F2
now let u be
set ;
( u in F1 implies u in F2 )assume A28:
u in F1
;
u in F2then reconsider u9 =
u as
Element of
Bags n ;
hence
u in F2
;
verum end;
then
F1 c= F2
by TARSKI:def 3;
hence
F1 = F2
by A23, A26, PRE_POLY:8; verum