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
  All(x,y,z,p) = All(x,All(y,z,p)) & Ex(x,y,z,p) = Ex(x,Ex(y,z,p));
