reserve A for QC-alphabet;
reserve p, q, r, s for Element of CQC-WFF(A);

theorem
  (( p '&' q ) => r ) => ( p => ( q => r )) in TAUT(A)
proof
  p => (( q => ( p '&' q )) => ((( p '&' q ) => r ) => ( q => r ))) in
  TAUT(A) & p => ( q => ( p '&' q )) in TAUT(A) by Th28,LUKASI_1:1,13;
  then
A1: p => ((( p '&' q ) => r ) => ( q => r )) in TAUT(A) by LUKASI_1:20;
  (p => ((( p '&' q ) => r ) => ( q => r ))) => ((( p '&' q ) => r ) => (
  p => ( q => r ))) in TAUT(A) by LUKASI_1:8;
  hence thesis by A1,CQC_THE1:46;
end;
