reserve A for QC-alphabet;
reserve sq for FinSequence,
  x,y,z for bound_QC-variable of A,
  p,q,p1,p2,q1 for Element of QC-WFF(A);
reserve s,t for bound_QC-variable of A;
reserve F,G,H,H1 for Element of QC-WFF(A);
reserve x,y,z for bound_QC-variable of A,
  k,n,m for Nat,
  P for ( QC-pred_symbol of k, A),
  V for QC-variable_list of k, A;

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;
