let p, q be Element of CQC-WFF ; :: thesis: (('not' p) => q) => ((q => p) => p) in TAUT
( (('not' ((q => p) => p)) => ((q => p) => p)) => ((q => p) => p) in TAUT & ((('not' ((q => p) => p)) => ((q => p) => p)) => ((q => p) => p)) => ((('not' p) => q) => ((q => p) => p)) in TAUT ) by Lm10, CQC_THE1:42;
hence (('not' p) => q) => ((q => p) => p) in TAUT by CQC_THE1:46; :: thesis: verum