The main supervisor must be a permanent member of the faculty at associate professor or professor level and an active researcher within the field in question. The main supervisor is formally appointed by the head of the Graduate School.
Co-supervisors yield guidance within a particular part of the project, in which they have a special expertise. A PhD student may have up to three co-supervisors. It is not required that co-supervisors are permanent members of the faculty, as long as they have relevant research qualifications within the research area. Please note that the faculty does not pay external supervisors.
It is a requirement from the Graduate School that a PhD student have at least one co-supervisor, besides the main supervisor.