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
  X|- p => q implies X|- (q => r) => (p => r)
proof
  assume
A1: X|- p => q;
  X|- (p => q) => ((q => r) => (p => r)) by CQC_THE1:59;
  hence thesis by A1,CQC_THE1:55;
end;
