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 Th7:
  q => ((q => p) => p) in TAUT(A)
proof
  ('not' p => q) => ((q => p) => p) in TAUT(A) & (('not' p => q) => ((q => p)
  => p)) => (q => ((q => p) => p)) in TAUT(A) by Lm11,Th6;
  hence thesis by CQC_THE1:46;
end;
