本論文考慮一個兩國、兩個多產品廠商不完全競爭模型，在廠商相互傾銷之下（reciprocal dumping）之下，每個廠商選擇最適的研發投入組合，而每個政府則決定最適研發補貼策略。本論文考慮一個三階段賽局：政府在第一階段制定對本國廠商的研發補貼（課稅），而第二階段與第三階段，廠商則分別決定研發的投入量和產量。

我們分析沒有貿易以及有貿易的情況。有趣的是，兩個情況下的結果基本上相當類似，無論是否進行貿易，政府對於廠商兩個產品的研發皆會進行補貼，但對於核心產品的研發則會補貼得更多。在最適的研發補貼之下，廠商也會投入更多在自己核心產品的研發投資上，這也將導致進行研發投資後，兩種產品的成本差異增加。

最後比較靜態分析指出，貿易成本增加如關稅或其他貿易壁壘則會讓兩個政府的補貼下降，廠商針對各商品的研發量下降，而政府對核心產品研發補貼的集中度與廠商對核心產品的研發集中度皆會增加。

關鍵字：相互傾銷、多產品廠商、研發組合、研發集中度、研發補貼

This paper considers s a two-country, two-firm imperfect competition model where firms engage in reciprocal dumping. Each firm strategically selects its optimal research and development (R&D) investment portfolio, while each government determines its optimal R&D subsidy strategy. The paper analyzes a three-stage game: in the first stage, governments set R&D subsidies (taxation) for domestic firms, while in the second and third stages, firms independently decide their R&D investment and output levels.

We analyze no trade case and some trade case. Interestingly, the results are quite similar in both cases. Regardless of whether there is trade or not, governments will provide subsidies for firms' R&D activities, with higher subsidies allocated to the R&D of core products. Under the optimal R&D subsidies, firms will also allocate more investment into the R&D of their core products, leading to an increase in cost differences between the two products after R&D investments.

Finally, through comparative static analysis, it is found that an increase in trade costs, such as tariffs or other trade barriers, will cause a decrease in subsidies provided by both governments. Firms' R&D investments in each product will also decrease, while the intensities of government subsidies on R&D of core products and firms' R&D investment for core products will both increase.

Keywords: reciprocal dumping, multiproduct firm, R&D portfolio, R&D intensity, R&D subsidy

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