reserve A,B for Ordinal,
        o for object,
        x,y,z for Surreal,
        n for Nat,
        r,r1,r2 for Real;

theorem
  uReal.r == 0_No implies r=0
proof
  assume uReal.r == 0_No;
  then 0 <= r <= 0 by SURREALN:51,47;
  hence thesis;
end;
