theorem
  S is (R5) (R8) implies (1.S)" <<>> 1.S
  proof
    assume
A1: S is (R5) (R8);
    take (1.S)"*1.S;
    thus (1.S)"*1.S =*=> (1.S)" by A1,Th2;
    thus (1.S)" * 1.S =*=> 1.S by A1,Th2;
  end;
