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

theorem
  0_No <= uInt.n
proof
  0 = n or 0 < n;
  then uInt.0 = uInt.n or uInt.0 < uInt.n by Th3;
  hence thesis by Def1;
end;
