Before revision:  The aim of this paperis to show a certain equivalence between these scheduling policiesfor the special case when the multiclass population have identical and exponential service requirements.
After revision:  In this paper, we propose two classes of policies, namely MPS (multiclass processor sharing) and MROS (multiclass random order service), that generalize the four policies mentioned above. For the special case when the multiclass population have identical and exponential service requirements.