My advice is to let it go. Don't make an issue over a 1/2 point deduction on a test. Look at it this way. You can make this a life and death issue with your teacher. You may even win if you press it hard enough. But what have you gained??? Just 1/2 a point but now you have an angry teacher who has lost face and who may mark your work even harder on another test or examination. It is not worth it.
Student or Learner