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
  p => (q => r) is valid & p => q is valid implies p => r is valid
proof
  assume that
A1: p => (q => r) is valid and
A2: p => q is valid;
  (p => q) => (p => r) is valid by A1,Th48;
  hence thesis by A2,CQC_THE1:65;
end;
