theorem Th106:
  |-_IPC (p => q) => (((p => FALSUM)=> FALSUM) => ((q => FALSUM)=> FALSUM))
proof
A1: (p => q) => ((q => FALSUM) => (p => FALSUM)) in IPC-Taut
      by Th70,Th81;
  ((q => FALSUM) => (p => FALSUM)) =>
  (((p => FALSUM) => FALSUM) => ((q => FALSUM)=> FALSUM))in IPC-Taut
    by Th70,Th81;
  hence thesis by A1,Th69,INTPRO_1:26;
end;
