抄録
A model is given for the evolution of a heterogeneous population of identical
living particles, divided into different classes. The model is dynamic, since the
partition of the population changes as the time goes on. The aim of this paper is to
determine the law of the lifetime of each particle given the number of dead particles up
to time t. This program is achieved by introducing the occupancy numbers, which are
defined as the cardinality of each class. Assuming that the partition is non-observable,
a filtering problem arises and the observation coincides with the cardinality of the class
of dead particles. A discussion is performed about discrete time approximations of the
filter.
