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 Th22:
  p => (q => r) in TAUT(A) & p => (r => s ) in TAUT(A) implies
   p => (q => s) in TAUT(A)
proof
  assume that
A1: p => (q => r) in TAUT(A) and
A2: p => (r => s ) in TAUT(A);
  p => ((q => r) => ((r => s) => (q => s))) in TAUT(A) by Th1,Th13;
  then p => ((r => s) => (q => s)) in TAUT(A) by A1,Th20;
  hence thesis by A2,Th20;
end;
