I was wondering that when there is a call for application for PhD candidates, how much of theory on a particular field does the professor usually expect the candidate to know?
I have seen situations discussed here itself, where the professors were interested in hiring applicants who already are well versed with the theory behind the project they are applying to. Is this universal? Or is that a particular case and there are others who allow the applicant to get used to the theory in the field in, say, 0.5-1 year or so.
Also, does it matter in terms of whether the candidate is a international applicant?
Edit: I narrowed the field I'm most interested in to be Computer Science. My target area for sending the applications is EU countries. With respect to the international applicant part, I am from India.