第一篇論文為「產品異質、空間差別訂價與空間聚集」。De Fraja and Norman (1993)發現當廠商在線性都市市場採行空間差別訂價時，廠商的均衡區位皆為聚集在市場之中點，且此一解為模型之「惟一解」。本文採用一個較 De Fraja and Norman (1993) 合理的服務全市場條件(market-serving condition)，重新檢視該文之均衡。本文發現若廠商採取空間差別訂價時，廠商之區位均衡可能是聚集解也可能是分離解，視運輸費率與產品異質程度而定。若給定產品之異質程度，則當運費費率較低時，廠商之最適區位為一聚集解；但當運輸費率提高到某一程度後，廠商之最適區位會向兩端移動而產生分離解，且此一分離之傾向會隨著產品異質程度降低而提高。
第二篇論文為「最適貿易政策、Cournot競爭與水平異質」，本文採用Hotelling的不完全覆蓋市場空間模型，假設產品的水平異質特性由廠商內生決定，建立一個三國二廠商的三階段貿易模型，探討廠商從事 Cournot 數量競爭下本國政府的最適單向出口政策。本文發現當產品的異質程度內生決定時，提高出口稅會創造一個水平異質效果，透過擴大產品之水平異質程度以降低競爭，進而提高價格與利潤水準，本國政府的最適單向出口政策為課徵出口稅，此結果與Eaton and Grossman (1986) 有很大的不同。再者，本文証明若短期內產品的異質程度來不及調整，則水平異質效果消失為零，本國政府的最適單向出口政策仍為出口補貼。此外，本文也發現當本國與外國廠商在第三國市場各自為區域獨占廠商時，本國政府的最適單向出口政策為自由貿易 (free trade)，與傳統非空間 (spaceless) 模型中的獨占廠商最適出口政策結論相同。
	第三篇論文為「產品標準化政策與貿易保護-二維空間模型之應用」，本文採用二維的空間模型，考慮水平異質特性的產品標準化政策，探討當廠商在市場從事出廠價格競爭時本國政府的最適產品標準化政策。本文發現隨著單位轉換成本愈高，本國政府的最適產品標準愈趨近於本國廠商的標準。尤其是當單位轉換成本為零時，本國政府的最適產品標準為市場之中點；當單位轉換成本大(等)於一時，本國政府的最適產品標準為本國產品標準。當單位轉換成本小於一時，標準化政策不必然會提高本國廠商之利潤，須視單位轉換成本

The essay is composed of three independent papers. The first paper is “Product Differentiation, Spatial Price Discrimination and Spatial Agglomeration”. De Fraja and Norman (1993) conclude that the two firms necessarily agglomerate at the market center, which is the unique locational equilibrium under spatially discriminatory pricing. Our paper challenges their definition of the market-serving assumption for being too restrictive and proposes a more reasonable one. Using the modified definition, this paper finds that the location configuration can be of either central agglomeration or dispersion under spatially discriminatory pricing, depending on the magnitude of the transport rate and the degree of product differentiation. 
The secondary paper is “Optimal Trade Policy, Cournot Competition and Horizontal Differentiation”. Introducing an uncovered market of the Hotelling’s linear city model, this paper constructs a three-country, two-firm trade model with a three-stage game to explore the unilateral optimal export policy under Cournot competition, as the degree of horizontal differentiation is endogenously determined. This paper shows that a rise in the export tax creates a horizontal-differentiation effect to mitigate competition via enlarging the degree of horizontal differentiation. This leads to the results that the optimal export policy of the domestic country is to levy a tax policy. 
The third paper is “Product Standardization Policy and Trade Protection- An Application of the Two-Dimensional Spatial Model”. This paper constructs a two-country, two-firm trade model to explore the optimal product standardization policy under Bertrand competition when products exhibit features of horizontal and vertical product differentiation. It shows that the optimal standard is 1/2 when the unit switch cost is zero, while equals the standard of the domestic firm when the unit switch cost is larger than one. It also shows that given the unit switch cost being smaller than one, the standardization policy does not protect domestic firm when the upper bound of consumers’ quality taste is small, while it does when the upper bound is large. Moreover, this paper proves that a rise in the quality difference between two products may lead to the result that the effect of the standardization policy from not protection to protection, when the upper bound lies in the intermediate range, say, 1.13   1.3.This gives an incentive for the government to impose an industrial policy for enlarging the magnitude of the quality difference.

表圖目錄…………………………………………………...........IV

第一章	  緒 論…… ……………………………………...……..1
1.1	研究動機與目的…………………………………………… 1
1.2	文獻回顧…………………………………………….……. 4
1.3	論文架構……………………………………………….....6

第二章	  產品異質、空間差別訂價與空間聚集………….……..8
    2.1  前言………………………………………………………… 8
    2.2  基本模型…………………………………………..……  11
    2.3  一般化模型…………………………………….………   18
    2.4  結論…………………………………………………….   22
    參考文獻…………………….……………………………………24

第三章　最適貿易政策、Cournot競爭與水平異質..............27
    3.1  前言…………………………………….……………...…27
    3.2  基本模型……………………………………………………31
    3.3  最適產品特性之決策……………………………………..37
    3.4  最適出口政策…………………………………………..  43
    3.5  結論………………………………………….…………...50
　　3.6  附錄………………………………………………………..51
    參考文獻………………………..………………….……………53

第四章　產品標準化政策與貿易保護-二維空間模型之應用…..…57
   4.1 前言…………………………………….…………………...57
    4.2  基本模型…………………………………………………. 61
    4.3  最適產品標準決策………………………………………..65
    4.4  產品標準化政策與貿易保護效果……………………… .68
      4.4.1  當單位轉換成本 b < 1的標準化政策..……..…  69
      4.4.2  當單位轉換成本 b > 1的標準化政策….………...79
    4.5  結論…………………….…………………………….…..81
    參考文獻……………………….…………………………………83

第五章 結論與建議….…… ……………………...……….…... 85
    參考文獻…………………………………………….……………88

黃鴻 (1997), “Hotelling模型的回顧與展望,” 經濟論文叢刊, 25 (2), 113-124。
林燕淑、黃鴻 (1998), “最適出口補貼與空間競爭策略性貿易政策,” 經濟論文, 26 (1), 1-18。
楊雅博、吳世傑、黃鴻 (2002), “規模報酬與最適貿易政策,” 經濟論文, 30 (1), 1-27。
楊雅博、黃鴻 (2003), “同質 Bertrand 競爭下的最適貿易政策,” 經濟論文, 31 (1), 73-89。
Aidt, T.S. (1998), “Political internalization of economic externalities and environmental policy,” Journal of Public Economics 69, 1-16.
Anderson, S.P., and De Palma, A. (1988), “Spatial Price Discrimination with Heterogeneous Products,” Review of Economic Studies 55, 573-92.
Anderson, S.P., and D.J. Neven (1991), “Cournot Competition Yields Spatial Agglomeration,” International Economic Review 32, 793-808.
Bandyopadhyay, S., S.C. Bandyopadhyay, and E.S. Park (2000), “Unionized Bertrand Duopoly and Strategic Export Policy,” Review of International Economics 8, 164-74.
Barrett, S., (1994), “Strategic environmental policy and international trade,” Journal of Public Economics 54, 325-38.
Berry S., and J. Waldfogel (2003), “Product Quality and Market Size,” NBER Working Paper Series 9675.
Boom A., (1995), “Asymmetric International Minimum Quality Standards and Vertical Differentiation,” Journal of Industrial Economics 43, 101-19.
Brander, J. A., and B.J. Spencer (1985), “Export Subsidies and International Market Share Rivalry,” Journal of International Economics 18, 83-100.
Chambers, R.G., and M., Weiss, (1992), “Revisiting Minimum quality standards,” Economic Letters 40, 197-201.
Chamorra Rivas, J. M., (2000), “Spatial dispersion in Cournot compeition,” Spanish Economic Review 2,145-52.
D’Aspremont, C., J. Gabzewicz, and J.-F., Thisse (1979), “On Hotelling,s Stability in Competition,” Econometrica 47, 1145-50.
Das, Satya P., and S. Donnenfeld, (1987), “Trade Policy and Its Impact on Quality of Imports: A Welfare Analysis,” Journal of International Economics 23, 77-90.
Das, Satya P., and S. Donnenfeld, (1989), “Oligopolistic Competition and International Trade: Quantity and Quality Restrictions,” Journal of International Economics 27, 299-318.
De Meza, D. (1986), “Export Subsidies and High Productivity: Cause or Effect?,”  Canadian Journal of Economics 347-50.
De Palma, A., V. Ginsburgh, Y.Y. Papageorgiou, and J.-F., Thisse (1985), “The Principle of Minimum Differentiation Holds Under Sufficient Heterogeneity,” Econometrica 53, 767-81.
De Fraja, G., and G. Norman (1993), “Product Differentiation, Pricing Policy and Equilibrium,” Journal of Regional Science 33, 343-63.
Dixit, A.K. (1984), “International Trade Policy for Oligopolistic Industries,” Economic Journal 94, 1-16.
Dixit, A.K., and J. Stiglitz (1977), “Monopolistic Competition and Optimum Product Diversity,” American Economic Review 67, 297-308.
Eaton, J., and G.M. Grossman (1986), “Optimal Trade and Industrial Policy under Oligopoly,” Quarterly Journal of Economics 101, 383-406.
Economides, N. (1984), “The Principle of Minimum Differentiation Revisited,” European Economic Review 24, 345-68.
Economides, N. (1986), “Nash Equilibrium in Duopoly with Products Defined by Two Characteristics,” Rand Journal of Economics 17, 431-439.
Economides, N., (1993), “Quality Variations in the circular model of variety-differentiated products,” Regional Sciences and Urban Economics 23, 235-257.
Farrell J, and G. Saloner, (1985), “Standardization, Compatibility, and Innovation,” Rand Journal of Economics 16, 70-83.
Friedman, J.M., and J.-F., Thisse, (1993), “Partial Collusion Fosters Minimum Product Differentiation,” RAND Journal of Economics 24, 631-45.
Ferreira, R.D.S., and J.-F. Thisse (1996), “Horizontal and Vertical Differentiation: The Launhardt Model,” International Journal of Industrial Organization 14, 485-506.
Fischer R., and P. Serra, (2000), “Standards and Protection,” Journal of International Economics 52, 377-400.
Gandal N., and O. Shy, (2001), “Standardization Policy and International Trade,” Journal of International Economics 53, 363-83.
Hamilton, J.H., J.F Thisse, and A. Weskamp (1989), “Spatial Discrimination: Bertrand vs. Cournot in a Model of Location Choice,” Regional Science and Urban Economics 19, 87-102.
Hotelling, H. (1929), “Stability in Competition,” Economic Journal 39, 41-57.
Ishikawa, J., and B.J. Spencer (1999), “Rent-shifting Export Subsidies with an Imported Intermediate Product,” Journal of International Economics 48, 199-232.
Jehiel, P., (1992), “Product Differentiation and Price Collusion,” International Journal of Industrial Organization 10, 633-43.
Klette, T.J. (1994), “Strategic Trade Policy for Exporting Industries：More General Results in the Oligopolistic Case,” Oxford Economic Papers 46, 296-310.
Krugman, P., (1991), “Increasing Returns and Economic Geography,” Journal of Political Economy 99, 483-499.
Kuhn, M., (2007), “Minimum Quality Standards and Market Dominance in Vertically Differentiated Duopoly,” International Journal of Industrial Organization 25, 275-90.
Lederer, P.J., and A.P. Hurter (1986), “Competition of Firms：Discriminatory Pricing and Location,” Econometrica 54, 623-40.
Liang, W.J., H. Hwang, and C.C. Mai (2006), “Spatial Discrimination: Bertrand vs. Cournot with Asymmetric Demands,” Regional Science and Urban Economics 36, 790-802.
Liang, W.J., and C.C. Mai, (2006), “Validity of the Principle of Minimum Differentiation under Vertical Subcontracting,” Regional Science and Urban Economics 36, 373-84.
Maggi G. (1996), “Strategic Trade Policies with Endogenous Mode of Competition,” American Economic Review 86, 237-258.
Mai, C.C., and H. Hwang (1988), “Optimal Export Subsidies and Marginal Cost Differentials,” Economics Letters 27, 279-82.
Mai, C.C., and S.K. Peng, (1999), “Cooperation vs. Competition in a Spatial Model,” Regional Science and Urban Economics 29, 463-72.
Matsushima, N., and D. Shimizu, (2005), “Spatial Cournot Competition and Economic Welfare: A Note,” Regional Science and Urban Economics 35, 658-70.
Matsushima, N., and T. Matsumura, (2006), “Mixed Oligopoly, Foreign Firms, and Location Choice,” Regional Science and Urban Economics, forthcoming.
Mayer, T., (2000), “Spatial Cournot competition and heterogeneous production costs across locations,” Regional Science and Urban Economics 30, 325-52.
Neary, J.P. (1994), “Cost Asymmetries in International Subsidy Games: Should Governments Help Winners or Losers?,” Journal of International Economics 37, 197-218.
Qiu, L.D. (1994), “Optimal Strategic Trade Policy under Asymmetric Information”, Journal of International Economics 36, 333-54.
Rhee, B.-D., A. De Palma, C. Fornell, and J.-F. Thisse, (1992), “Restoring the Principle of Minimum Differentiation in Product Positioning,” Journal of Economics and Management Strategy 1, 475-505.
Ronnen, U., (1991), “Minimum Quality Standards, Fixed Costs, and Competition,” Rand Journal of Economics 22, 490-504.
Salop, S., (1979), “Monopolistic Competition with Outside Goods,” Bell Journal of Economics 10, 141-56.
Shimizu D. (2002), “Product Differentiation in Spatial Cournot Markets,” Economics
Letters 76, 317-22.
Singh, N., and X. Vives (1984), “Price and Quantity Competition in a Differentiated Duopoly,” Rand Journal of Economics 15, 546-54.
Spence, A.M. (1976), “Product Selection, Fixed Costs and Monopolistic Competition,” Review of Economic Studies 43, 217-36.
Spencer, B.J., and R.W. Jones (1991), “Vertical Foreclosure and International Trade Policy,” Review of Economic Studies 58, 153-70.
Stahl, K., (1982), “Location and Spatial Pricing Theory with Nonconvex Transportation Cost Schedules,” The Bell Journal of Economics 13, 572-82.
Sturm D.M., (2007), “Product Standards, Trade Disputes, and Protectionism,” Canadian Journal of Economics 39, 564-81.
Sydsaeter, K., and P.J. Hammond, (1995), Mathematics for Economic Analysis, Prentice-Hall International, London.
Tabuchi, T., (1994), “Two-stage two-dimensional Spatial Competition Between Two Firms,” Regional Science and Urban Economics 24, 207-27.
Yang, B.S., W.J. Liang, H. Hwang, and C.C. Mai (2007), “A General Analysis of Spatial Cournot Competition in a Linear City Model,” Tamkang University, Working Paper.
Zhang, Z.J., (1995), “Price-matching Policy and the Principle of Minimum Differentiation,” Journal of Industrial Economics 43, 287-99.
Zhou, D., B.J. Spencer, and I. Vertinsky (2002), “Strategic Trade Policy with Endogenous Choice of Quality and asymmetric Costs,” Journal of International Economics 56, 205-32.