本研究主要目的為探討垂直相關產業架構下廠商的競爭策略均衡。研究結果顯示，在上下游專業分工的產業架構中，廠商選擇數量競爭是Nash均衡結果。但在垂直整合供應商(VIP)產業架構下，我們的研究發現市場競爭均衡結果是廠商都會選擇價格競爭，造成這項結果的原因乃是因為在VIP的架構下，VIP廠商能夠利用上游市場的壟斷力，從下游競爭對手的產出擴張中獲取利潤，從而使得下游市場的競爭程度趨緩，遂而使得價格策略成為雙方的優勢策略。更進一步地，我們還將垂直相關產業架構擴展至競爭廠商間存著交叉持股的情況，並且發現上述的兩種均衡結果可能不再成立。具體而言，在上下游專業分工的產業架構中，若僅有一家廠商單邊持有對方股份，且持股比例過高與廠商產品接近同質性下，就會出現一方廠商選擇數量競爭，另一方則選擇價格競爭。另一方面，在VIP的產業架構下，當考慮廠商間的交叉持股時，我們發現若廠商間都互相持有對方股權且持股比例相對高時，兩廠商皆選擇數量競爭或兩廠商皆選擇價格競爭皆可成為均衡結果。

The purpose of this study is to explore the competitive strategy equilibrium of firms in a vertically related industry structure.The research findings that in a structure characterized by upstream and downstream specialization, both firms choosing quantity competition is a Nash equilibrium . However, in the vertical integration of suppliers (VIP) industry structure, we find that the both firms choose price competition. This outcome arises because, within the VIP framework, VIP firms can leverage the monopoly power of the upstream market to gain profits from the output expansion of downstream competitors, thereby reducing the level of competition in the downstream market and making price strategies the dominant strategy for both firms. Furthermore, we extend the vertically related industry structure to situations where competing firms have cross-shareholdings and discover that the aforementioned two equilibrium outcomes may no longer hold. Specifically, in an industry structure characterized by upstream and downstream specialization, if only one firm holds shares in the other and the shareholding ratio is excessively high while the products of the firms are nearly homogeneous, one firm may choose quantity competition while the other opts for price competition. On the other hand, in the VIP industry structure, when considering cross-shareholdings among firms, we find that if firms mutually hold each other's shares and the shareholding ratios are relatively high, both firms choose quantity competition or both firms choose price competition as equilibrium outcomes.

論文審定書 i
誌謝 ii
中文摘要 iii
英文摘要 iv
1. 緒論 1
2. 專業上游供應商 6
2.1 q-q game 7
2.2 p-p game 9
2.3 q-p game 11
2.4 p-q game 13
3. 垂直整合廠商 17
3.1 q-q game 17
3.2 p-p game 18
3.3 q-p game 20
3.4 p-q game 22
4. 延伸討論：交叉持股 25
5. 結論 28
附錄 29
參考文獻 30

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