let p, q, r be Element of CQC-WFF ; :: thesis: ( (p '&' q) => r is valid implies p => (q => r) is valid )
A1: ((p '&' q) => r) => (p => (q => r)) in TAUT by PROCAL_1:31;
assume (p '&' q) => r in TAUT ; :: according to CQC_THE1:def 10 :: thesis: p => (q => r) is valid
hence p => (q => r) in TAUT by A1, CQC_THE1:46; :: according to CQC_THE1:def 10 :: thesis: verum