本文探討在雙占廠商進行製程研發, 允許研發量角解的情況下, 廠商的最適決策行為。過去關於製程研發的研究, 對廠商的研發效率與生產成本兩參數皆有範圍限制, 然而, 不論是研發效率, 或者成本的大小, 都屬外生變數, 並非研究者能控制的, 因此本研究放寬這些對外生變數的限制, 討論在各種情況下, 廠商的最適決策為何。
依照廠商成本的不同, 我們將成本組合劃分為六個區域, 分別討論廠商的研發決策與市場型態。在以往文獻假設兩家廠商完全對稱的情況下, 廠商的最適研發量相同且為內部解, 但根據本文研究結果, 我們發現, 內部解並非都是穩定的均衡, 即使兩家廠商條件完全相同, 最適研發決策仍可能有所不同。另外本文也發現, 在未進行研發時, 成本高的廠商, 本因退出市場, 但該廠商能透過製程研發來降低成本, 藉此在市場上生存, 不僅如此, 甚至有機會藉著優越的研發能力,
逆轉情勢, 迫使原本的獨占廠商退出市場。

Given the theoretical possibility that corner solutions in process R&D may be present, this thesis reconsiders duopoly firms’ investment and production strategies in a Cournot
model and shows how previous studies incorrectly deal with the corner solution problem by restricting the range of parameters for both R&D efficiency and marginal cost.
In a more general setting that the duopoly firms may be asymmetric, we explore their best-response functions under various combinations of R&D efficiency and marginal cost
parameters. For analysis convenience, we firstly divide the cost combinations into six regions, and then in each region discuss the equilibrium market structure along with firms’
equilibrium strategies under all possible R&D efficiency combinations.
Previous studies only discuss the symmetric case and claim that the amounts of R&D investment are interior and identical. In contrast, we find that inner solutions can be
unstable, and the optimal R&D investment decisions can be asymmetric even if the two firms are identical. Furthermore, the cost-disadvantaged firm that was prevented from the market without the introduction of R&D may now participates in the market when its R&D efficiency is relatively high, while the cost-advantaged firm that plays as a monopoly without the introduction of R&D may now be expulsed from the market.

Matsushima, Noriaki, Yasuhiro Sato, and Kazuhiro Yamamoto (2013), “Horizontal Mergers, Firm Heterogeneity, and R&D Investments”, The B.E. Journal of Economic Analysis & Policy, 13(2), 959–990.

Mukherjee, Arijit (2006), “Cross-Border Merger and Domestic Welfare”, Economics Bulletin, 6(16), 1–8.

Mukherjee, Arijit and Prabal Roy Chowdhury (2013), “Innovation and Social Desirability of Merger”, Economics Bulletin, 33(1), 348–360.

Sinha, Uday Bhanu (2013), “On R&D Information Sharing and Merger”, Economic Modelling, 32, 369–376.

Wong, Kit Pong and Maurice K.S. Tse (1997), “Mergers and investments in cost reduction with private information revisited”, International Journal of Industrial Organization, 15, 629–634.