Production indices obtained by a myopic policy for non-Markovian dynamics

The urgency indices which are used to schedule multiclass production system s are calculated for production flows characterized by M/G/1 dynamics. The calculation of the indices is based on a myopic policy for which the time l ook-ahead distribution is chosen to be a Gamma distribution with its first two moments matching either those of the waiting time or the busy period di stributions of the M/G/1 queue. For a single item, the priority index can a lso be used to determine the position of an optimal hedging stocks. It is s hown that only the priority indices obtained from waiting time took-ahead p roduce consistent results with the optimal values of the hedging obtained i n solving directly the optimal control problem for a markovian dynamics. Ad ditionally, consistency is also guaranteed when the diffusive approximation is used to discuss the heavy traffic regimes. (C) 2001 Elsevier Science BY . All rights reserved.