reserve A for QC-alphabet;
reserve p, q, r, s, t for Element of CQC-WFF(A);
reserve X for Subset of CQC-WFF(A);

theorem Th13:
  q in TAUT(A) implies p => q in TAUT(A)
proof
  q => (p => q) in TAUT(A) by Th5;
  hence thesis by CQC_THE1:46;
end;
