I'm a Physics Ph.D. student and I have been studying one paper and had some doubt in one point. More specifically the author defines a concept in a way which is a little bit different from other texts I've read before and I'm failing to understand why it is the same thing. I believe I would benefit from understanding this correctly.
More specifically to the situation, the paper has been posted on arXiv and is really some lecture notes which were latter transformed into a book. The author also says to email any questions or corrections to his email in the first page.
Considering this situation (that it is really some lecture notes later transformed into a book and that the author says to email any questions to his email) is it considered ok to ask it?
More generally, if it is really some paper published in some journal, and if there is nothing written saying that "any questions should be sent to that email", is it still ok to ask of the author in case of any doubts?
My main issue is that I fear if the author might consider my doubt something "too basic". Is that really a problem?