Let U a set of elementary events, . One calls possibility measure denoted a function defined on the set of all parts of , taking values in such as:
A possibility degree means that the event is completely possible, inversely means that is impossible.
A possibility distribution assigns to each element of a
. The distribution is normalized: .
A guaranteed possibility measure is a function defined on the set of all parts of , taking values in , such as:
Relation between possibility degree and guaranteed possibility degree:
, all elementary events are
guaranteed possible at level .
Guaranteed possibility distributions are denoted .
Interpretation of possibility degree and guaranteed possibility degree