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 Th16:
  s => (q => p) in TAUT(A) & q in TAUT(A) implies s => p in TAUT(A)
proof
  assume s => (q => p) in TAUT(A);
  then q => (s => p) in TAUT(A) by Th15;
  hence thesis by CQC_THE1:46;
end;
