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

theorem Th35:
  ( p => r ) => (( q => r ) => (( p 'or' q ) => r)) in TAUT(A)
proof
  set AA = ( 'not' r => 'not' p );
  set B = ( 'not' r => 'not' q );
  set C = ( 'not' r => ( 'not' p '&' 'not' q ));
  set D = (( p 'or' q ) => r );
  set E = q => r;
A1: AA => ( B => C) in TAUT(A) by Th33;
  C => ('not' ( 'not' p '&' 'not' q ) => r ) in TAUT(A) by LUKASI_1:31;
  then C => D in TAUT(A) by QC_LANG2:def 3;
  then
A2: B => ( C => D ) in TAUT(A) by LUKASI_1:13;
  B => ( C => D ) => (( B => C ) => ( B => D )) in TAUT(A) by LUKASI_1:11;
  then ( B => C ) => ( B => D ) in TAUT(A) by A2,CQC_THE1:46;
  then AA => ( B => D ) in TAUT(A) by A1,LUKASI_1:3;
  then
A3: B => ( AA => D ) in TAUT(A) by LUKASI_1:15;
  E => B in TAUT(A) by LUKASI_1:26;
  then E => ( AA => D ) in TAUT(A) by A3,LUKASI_1:3;
  then
A4: AA => ( E => D ) in TAUT(A) by LUKASI_1:15;
  (p => r) => AA in TAUT(A) by LUKASI_1:26;
  hence thesis by A4,LUKASI_1:3;
end;
