theorem Th76:
  |-_IPC (p => FALSUM) => (p => q)
proof
A1: (FALSUM => q) => ((p => FALSUM) => (p => q)) in IPC-Taut by INTPRO_1:22;
   FALSUM => q in IPC-Taut by INTPRO_1:def 14; then
  (p => FALSUM) => (p => q) in IPC-Taut by A1,INTPRO_1:def 14;
  hence thesis by Th69;
end;
