Each student will be assigned two mentors, one professor in his/her own discipline and one from a different subject. The mentors are usually the group leaders of the project the PhD student works with. Thus, they are the PIs, member of GSISH faculty or member of GSISH international faculty.  Typically these two mentors are also the PhD supervisors. The student and the mentors negotiate and agree on an individual training schedule and on a thesis plan including milestones based on the theses proposal presented by the student at the beginning of the project.