  We introduce a new foundation rank based in the relation of dividing between
partial types. We call DU to this rank. We also introduce a new way to define
the D rank over formulas as a foundation rank. In this way, SU, DU and D are
foundation ranks based in the relation of dividing. We study the properties and
the relations between these ranks. Next, we discuss the possible definitions of
a supersimple type. This is a concept that it is not clear in the previous
literature. In this paper we give solid arguments to set up a concrete
definition of this concept and its properties. We also see that DU
characterizes supersimplicity, while D not.
