let p, q be Element of CQC-WFF ; :: thesis: ((p => q) => p) => p in TAUT
( (('not' p) => (p => q)) => (((p => q) => p) => p) in TAUT & ((('not' p) => (p => q)) => (((p => q) => p) => p)) => ((p => (('not' p) => q)) => (((p => q) => p) => p)) in TAUT ) by Lm11, Lm13;
then ( p => (('not' p) => q) in TAUT & (p => (('not' p) => q)) => (((p => q) => p) => p) in TAUT ) by CQC_THE1:43, CQC_THE1:46;
hence ((p => q) => p) => p in TAUT by CQC_THE1:46; :: thesis: verum