reserve A,B,O for Ordinal,
        o for object,
        x,y,z for Surreal,
        n,m for Nat;
reserve d,d1,d2 for Dyadic;
reserve i,j for Integer,
        n,m,p for Nat;
reserve r,r1,r2 for Real;

theorem Th74:
  No_uOrdinal_op A in Day A
proof
  born No_uOrdinal_op A = A by Th73;
  hence thesis by SURREAL0:def 18;
end;
