Assigning patients to rooms is a fundamental task in hospitals
and, especially, within wards. For this so-called patient-to-room assignment
problem (PRA) many heuristics have been proposed with a large variety
of dierent practical constraints. However, a thorough investigation of the
problem's structure itself has been neglected so far. In this paper, we present
insights about the basic, underlying combinatorial problem of PRA with a
focus on minimizing the number of patient transfers which occur if patients
have to change rooms during their stay. Particularly, we prove that in the
case of double bedrooms, each patient has to be transferred at most once.