This paper presents results about the optimal order interval in a context
of fuzzy information about inventory management. The classical inventory
model is based on well known cost and demand rate. In practice, this
accurate estimation is very difficult to obtain, even impossible.
Consequently, we propose a solution, not optimal in a classical sense,
but allowing to choose an action which is not far from the optimal policy
whatever the economic parameters may be. These parameters belong to a field
which represents the error of estimation, this field is important to choose
the solution.