reserve A,B,O for Ordinal,
        o for object,
        x,y,z for Surreal,
        n,m for Nat;

theorem Th11:
  uInt.1 = 1_No
proof
  uInt.(1+0) = [{uInt.0},{}] by Def1
  .= [{0_No},{}] by Def1;
  hence thesis;
end;
