let p, q, s be Element of MC-wff ; :: thesis: ( p => q in IPC-Taut implies (s 'or' p) => (s 'or' q) in IPC-Taut )
assume A1: p => q in IPC-Taut ; :: thesis: (s 'or' p) => (s 'or' q) in IPC-Taut
(p => q) => ((s 'or' p) => (s 'or' q)) in IPC-Taut by Th62;
hence (s 'or' p) => (s 'or' q) in IPC-Taut by A1, Def14; :: thesis: verum