Abstract
Recently, some studies taking account of the substitutional characteristics among commodities have been made in the field of the multi-commodity inventory system. These studies have assumed that the seller can not control the customers' substitutional purchasing action. Therefore, the substitutional sales promotion has not been studied for the purpose of increasing the profit and improving the service ratio. In this study, it is assumed that the seller can control the customers' substitutional purchasing action by means of price discount. And the optimal price discount rate is obtained for the customers' various substitutional purchasing actions so as to maximize the total expected profit. Consequently, the sellers' profit is increased and the service ratio is improved.
