theorem
  QuantNbr('not' p) = QuantNbr(p)
proof
deffunc F(Element of CQC-WFF(A)) = QuantNbr($1);
A1: for p being Element of CQC-WFF(A),
   d being Element of NAT holds d = F(p)
iff ex F being Function of CQC-WFF(A), NAT st d = F.p & F.VERUM(A) = 0 &
for r,s,x,k
for l being CQC-variable_list of k,A for P being QC-pred_symbol of k,A holds
F.(P!l) = A(k,P,l) & F.('not' r) = N(F.r) & F.(r '&' s) = C(F.r,F.s) &
F.All(x,r) = Q(x,F.r) by Def6;
  thus F('not' p) = N(F(p)) from CQC_LANG:sch 7(A1);
end;
