  In this paper we introduce and analyse, from a game theoretical perspective,
several multi-agent or multi-item continuous review inventory models in which
the buyers are exempted from ordering costs if the price of their orders is
greater than or equal to a certain amount. For all models we obtain the optimal
ordering policy. We first analyse a simple model with one firm and one item.
Then, we study a model with one firm and several items, for which we design a
procedure based on cooperative game theory to evaluate the impact of each item
on the total cost. Then, we deal with a model with several firms and one item
for each firm, for which we characterise a rule to allocate the total cost
among the firms in a coalitionally stable way. Finally, we discuss a model with
several firms and several items, for which we characterise a rule to allocate
the total cost among the firms in a coalitionally stable way and to evaluate
the impact of each item on the cost that would be payable to each firm when
using the allocation rule. All the concepts and results of this article are
illustrated using data from a case study.
