Parlar and Berkin(1991) introduce the first of a series of models
that incorporate supply disruptions into classical inventory models.
They study the EOQD:anEOQ-like system in which the supplier
experiences intermittent failures.Demands are lost if the retailer has
insufficient inventory to meet them during supplier failures.The
retailer follows a zero-inventory ordering(ZIO)policy.Their cost
function was shown to be incorrect in two respects by Berk and
Arreola-Risa(1994), who propose a corrected cost function.It is their
function that we approximate in this paper.