本文以產品系統的空間競爭模型為架構，以兩個不同的面向進行分析：一為完全不考慮互補產品廠商合併下，分析三家廠商區位選擇的關聯特質及不同的市場力量對廠商區位選擇造成的影響。另一為考慮互補產品廠商預期未來有機會合併時，考量整體市場的均衡如何受到影響。藉此可分析台灣地區產業外移的問題及政府採取的政策是否能有效達成目的。文中將產品的互補性與替代性競爭的概念結合在一起，為本研究與過去相關的研究最大的不同。
根據本模型，在完全不考慮互補產品廠商合併時，互補產品廠商的區位選擇只受到競爭廠商的影響，與主產品廠商之區位選擇無關。主產品廠商的區位選擇則受互補產品廠商的區位選擇所影響。也就是說，無論主要產業是否會根留台灣，次要產業的區位選擇都不受其影響；若政府無法控制次要產業的外移，主要產業也將有機會外移至其他地區。此外，無論廠商在共享剩餘的分配比例為何，都不會影響互補產品廠商的區位選擇，只會影響主產品廠商的區位選擇。亦即，政府無法藉由干預剩餘分配的比例來影響次要產業的區位選擇，但還是能透過干預政策影響主要產業的區位。
若廠商有合併預期且不必然發生時，主產品廠商就不會選擇區位於市場中心，造成運輸成本的提高。但合併必定發生時，主產品廠商雖然會選擇成本極小化的區位，但互補產品廠商卻因區位的移動使運輸成本上升。也就是說，政府雖然可透過次要產業的合併政策使主要產業留在台灣，但卻必須負擔整體社會福利的損失。

This research regards spatial competition model of one product system as the structure to analyze two scenarios: first, we explores the properties of firms’ equilibrium location choices while there’s no possibility of merger, and the influences of different market power on firms’ location choices. In the second scenario, we study how the firms’ equilibrium location choices were affected by the possibility of merger. The results indicate that under certain circumstances, government’s policy regard emigratory industries in Taiwan may not be efficient. This research is the first one that combines the conceptions of complementarity and substitutability.
The main result is that without the possibility of merger, the location choices of competitive firms are affected not only by complementarity, but by substitutability. However, the location choice of the firm producing main product would be affected by the choice of competitive firms only. It implies that whether main industry roots in Taiwan or not, the location choice of secondary industries won’t be affected. Consequently, government can’t control the emigration of secondary industries so that main industry would have opportunities to emigrate. Also, we can find that the shares of joint surplus won’t affect the location choices of the competitive firms, but will affect the firm producing main product. Therefore, government could draw firms in the main industry via intervening the surplus allocation but can’t influence the location choices of firms in the secondary industries.
When competitive firms expects merger in the future, the firm producing main product may not locate at the center of market, which leads to higher transportation costs and lower social welfare. As merger is definitely happened, the firm producing main product will choose cost-minimizing location, but the locations of competitive firms lead to higher transportation costs. Therefore, keeping main industry nests in Taiwan must bear the losses of social welfare.

Carlton, D. W. and M. Waldman, “The strategic use of tying to preserve and create market power in evolving industries,” RAND Journal of Economics, Vol. 33, No. 2 (2002), pp. 194-220.
d’Aspremont, C., J. J. Gabszewicz and J.-F. Thisse, “On Hotelling’s ‘Stability in competition’,” Econometrica, Vol. 47, No. 5 (1979), pp. 1145-1150.
Eaton, B.H., “Spatial competition revisited,” The Canadian Journal Economics, Vol. 5, No. 2 (1972), pp. 268-278.
Farrell, J. and M. L., Katz, “Innovation, rent extraction, and integration in systems markets,” The journal of industrial economics, Vol. XLVIII, No. 4 (2000), pp. 413-432.
Gupta, B., “Sequential entry and deterrence with competitive spatial price discrimination,” Economics letters, Vol. 38 (1992), pp. 487-490.
Gupta, B., J. S. Heywood and D. Pal, “Duopoly, delivered pricing and horizontal mergers,” Southern Economic Journal, Vol. 63, No. 3 (1997), pp. 585-593.
Gupta, B., J. S. Heywood and D. Pal, “Strategic behavior downstream and the incentive to integrate: A spatial model with delivered pricing,” International Journal of Industrial Organization, Vol. 13, (1995), pp. 327-334.
Gupta, B., A. Kats and D. Pal, “Upstream monopoly, downstream competition and spatial price discrimination,” Regional Science and Urban Economics, Vol. 24, (1994), pp. 529-542.
Hotelling, H., “Stability in competition,” The Economic Journal, Vol. 39, No. 153 (1929), pp. 41-57.
Hurter, A. P. and P. J., Lederer, “Spatial duopoly with discriminatory pricing,” Regional Science and Urban Economics, Vol. 15 (1985), pp. 541-553.
Kats, A., “More on Hotelling’s stability in competition,” International Journal of Industrial Organization, Vol. 13 (1995), pp. 89-93.
Matsushima, N., “Cournot competition and spatial agglomeration revisited,” Economics Letters, Vol. 73 (2001), pp. 175-177.
Pal, D., “Does Cournot competition yield spatial agglomeration,” Economics Letters, Vol. 60 (1998), pp. 49-53.
Pinto, J.V., “Launhardt and location theory : Rediscovery of a neglected book,” Journal of Regional Science, Vol. 17 (1977), pp. 17-29.
Rothschild, R., “Merger under spatial competition,” Urban Studies, Vol. 37, No. 3 (2000), pp. 443-449.
Salop, S.C., “Monopolistic competition with outside goods,” The Bell Journal of Economics, Vol. 10 (1979), pp. 141-156.
Smithies, A., “Optimum location in spatial competition,” The Journal of Political Economy, Vol. 41 (1941), pp. 423-39.
Whinston, M. D., “Tying, foreclosure, and exclusion,” The American Economic Review, Vol. 80, No. 4 (1990), pp. 837-859.