let p, q, r, s be Element of CQC-WFF ; :: thesis: (p => (q => r)) => ((s => q) => (p => (s => r))) in TAUT
( ((((q => r) => (s => r)) => (p => (s => r))) => ((s => q) => (p => (s => r)))) => ((p => (q => r)) => ((s => q) => (p => (s => r)))) in TAUT & (((q => r) => (s => r)) => (p => (s => r))) => ((s => q) => (p => (s => r))) in TAUT ) by Lm1;
hence (p => (q => r)) => ((s => q) => (p => (s => r))) in TAUT by CQC_THE1:82; :: thesis: verum