let p, q, r be Element of CQC-WFF ; :: thesis: ((p => q) => r) => ((r => p) => p) in TAUT
( ((p => q) => p) => p in TAUT & (((p => q) => p) => p) => (((p => q) => r) => ((r => p) => p)) in TAUT ) by Lm14, Lm15;
hence ((p => q) => r) => ((r => p) => p) in TAUT by CQC_THE1:46; :: thesis: verum