Have you ever graded? If you have you would know that there is no such thing as "the correctness" in anything that isn't close to perfect. The OP had to decide

Have you ever graded? If you have you would know that there is no such thing as "the correctness" in anything that isn't close to perfect. The OP had to decide to give a number somehow to something that was in small parts right, but completely misguided. And then they wrote a long comment explaining the problem. That's far more useful to the student then just numbers. Maybe the student could actually read the comment and learn from it. Any violation of the intellectual promise in OP is from the student who doesn't put in the effort to learn.