let p, q be Element of MC-wff ; :: thesis: (p '&' q) => p is valid_IPC
(p '&' q) => p in IPC-Taut

proof

IPC-Taut is IPC_theory ;
hence (p '&' q) => p in IPC-Taut ; :: thesis: verum

end;

hence (p '&' q) => p is valid_IPC ; :: thesis: verum