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);

theorem Th1:
  the_argument_of 'not' p = p
proof
  'not' p is negative;
  hence thesis by QC_LANG1:def 24;
end;
