I just start to learn coq and I basically copied the code (?) from what the professor showed in the class but it never worked on my laptop! I have no idea why it keep telling me that the reference y was not found in the current environment. And there is only two sentences(?) in my coqIDE:
Require Export Utf8.
Notation "x->y" :=(x->y)(at level 99).
I've read some webpages asking similar questions but I don't think we had the same problem. If I'm wrong, sorry about that. In addition, could you please tell me what does "Utf8" and "at level 99" suppose to mean??
I know these are stupid questions but I just don't understand. Thank you for taking a look at it:)
