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);

theorem
  H is biconditional implies H is conjunctive & the_left_argument_of H
  is conditional & the_right_argument_of H is conditional
by Th4;
