let p, q, s be Element of MC-wff ; :: thesis: (p => q) => ((p '&' s) => (q '&' s)) in IPC-Taut
A1: ((p '&' s) => q) => ((p '&' s) => (q '&' s)) in IPC-Taut by Th43;
(p => q) => ((p '&' s) => q) in IPC-Taut by Th42;
hence (p => q) => ((p '&' s) => (q '&' s)) in IPC-Taut by A1, Th26; :: thesis: verum