let p, q, t be Element of CQC-WFF ; :: thesis: (('not' p) => q) => (t => ((q => p) => p)) in TAUT
( t => ((('not' p) => p) => p) in TAUT & (t => ((('not' p) => p) => p)) => ((('not' p) => q) => (t => ((q => p) => p))) in TAUT ) by Lm4, Lm8;
hence (('not' p) => q) => (t => ((q => p) => p)) in TAUT by CQC_THE1:82; :: thesis: verum