theorem Th41:
  not H is_immediate_constituent_of VERUM(A)
proof
  not ( VERUM(A) is negative or VERUM(A) is conjunctive
     or VERUM(A) is universal) by QC_LANG1:20;
  then not ((VERUM(A) = 'not' H)
        or (ex H1 st VERUM(A) = H '&' H1 or VERUM(A) = H1 '&' H)
        or (ex x being bound_QC-variable of A st VERUM(A) = All(x,H)));
  hence thesis;
end;
