不對稱廠商在直線市場之數量競爭與區位選擇

假設在直線市場上有三家採取數量競爭之廠商，而消費者均勻分布於此市場上；本研究採用區位－數量賽局理論，首先探討此三家廠商在生產同質或互補商品時，其中兩家廠商會形成合作瓜分市場之條件；進而分析此三家廠商如何決策其最佳區位。在線性需求函數假設下，本文得到以下結論：無論產品為替代或互補關係，如果運輸成本相當高時，兩家廠商有形成相互合作之誘因；而單一競爭廠商必定會選擇區位於直線市場之中間(2/1)；兩合作廠商則以單一競爭廠商為中心左右兩側等距分散區位。其次，在產品為完全替代（互補）時，當每單位運輸成本增大時，兩家合作廠商會選擇與競爭對手略微遠離（接近）的地點來區位。

關鍵字

不對稱廠商家數；直線市場；空間競爭；區位－數量賽局

並列摘要

Consider a three-firm model of spatial competition in which consumers are uniformly distributed along a line segment. Two of the three firms have the opportunity to cooperate to maximize their joint profits. In two-stage non-cooperative Cournot game with location choice, this study first derives the necessary condition in which two of the firms cooperate rather than make independent decisions regarding quantities and locations. This study then identifies the optimal locations of the three firms. Under the linear demand assumption, this study shows the following: First, when the transportation cost is high, two of the firms have an incentive to cooperate. Second, whether the products among competitive firms are substitutes or complements, a rival will be located at the center, while the two cooperating firms will be located equidistant from the rival firm. Furthermore, when the products are substitutes (complements) and the transportation cost are increased, the two cooperating firms will move slightly away from (closer to) their competitor.