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 Th8:
  (s => (q => p)) => (q => (s => p)) in TAUT(A)
proof
  q => ((q => p) => p) in TAUT(A) & (q => ((q => p) => p)) => ((s => (q => p)
  ) => (q => (s => p))) in TAUT(A) by Lm2,Th7;
  hence thesis by CQC_THE1:46;
end;
