let p, q, r be Element of CQC-WFF ; :: thesis: ( p => (q => r) is valid implies (q '&' p) => r is valid )
assume p => (q => r) in TAUT ; :: according to CQC_THE1:def 10 :: thesis: (q '&' p) => r is valid
then p => (q => r) is valid by CQC_THE1:def 10;
then (p '&' q) => r is valid by Th1;
then A1: (p '&' q) => r in TAUT by CQC_THE1:def 10;
(q '&' p) => (p '&' q) in TAUT by CQC_THE1:45;
hence (q '&' p) => r in TAUT by A1, LUKASI_1:3; :: according to CQC_THE1:def 10 :: thesis: verum