“…Our study covers many studies on promotions [2, 7, 10, 13, 16-18, 20, 21, 27], promotional period [29]. From the perspective of promotion methods, including rebate promotion [16], price discounts [1,2,12,13,21,22,25], gift card promotion [12,13], and freebie promotion [7,10,17,21], our work is mainly related to the last type of promotion. The studies related to promotion can be divided into two categories.…”