空間競爭之研究

Essays on Spatial Competition

孫嘉宏(Chia-Hung Sun)

指導教授 ： 賴孚權

國立臺北大學/社會科學學院/經濟學系/博士(2009年)

摘要

本論文涵蓋了四篇與空間競爭相關之文章，分別建構在不同的空間型態與廠商的競爭策略之上。
論文第二章題目為「方向性運輸限制下的圓形城市空間 Cournot 競爭」，探討的是廠商在圓形城市中，只往同一個方向運輸商品下的空間 Cournot 競爭，研究結果發現，當雙占廠商往不同的方向運輸商品，或是個別廠商可以選擇其商品的運輸方向時，廠商聚集在圓形城市中的同一個區位是唯一的均衡結果，而此種聚集的區位均衡與文獻上的發現是大相逕庭的。其次，本章也指出，廠商透過彼此間運輸成本的差異來減緩數量競爭，是造成此種區位聚集型態的主要原因。
論文第三章題目為「空間分離市場中 Cournot 競爭與經濟福利的一般性分析」。本章指出，在空間分離市場中，雙占廠商間的區位差異極大化，不僅可達到社會最適，也是唯一可能存在的區位均衡。在政策意涵方面，廠商彼此間區位差異所導致的運輸成本差異，同時是整個社會與經濟個體的偏好，而這也隱含著在空間分離市場中，政府無需干預廠商的區位選擇。
論文第四章題目為「論品質變異與極大化多樣性 (區位) 差異」。本章指出，在子賽局完美納許均衡的嚴謹定義之下，Economides (1989) 模型中的區位均衡並不存在，其中的關鍵在於在既定的對手區位之下，個別廠商區位選擇的最適反應並不存在。其次，本章也指出，只要對 Economides (1989) 模型中的運輸成本函數形式，以及對賽局架構作些許的修正，即能解決此均衡不存在的問題。
論文第五章題目為「多個參賽者依序進入的間斷型方向性市場」。本章探討三個以上的參賽者在方向性市場中的競爭行為，研究結果發現，由於參賽者在方向性市場中區位選擇的最適反應並不唯一，因此存在複均衡結果，且任何參賽者皆有可能在方向性市場中獲利。然而，透過 Spagat (1992) 所提出之 “宣告的均衡” (validated equilibrium)，以及本章所提出之 “報酬排序視為第二決定因子的字典型序列偏好關係參賽者” 等均衡定義的精鍊，我們發現在方向性市場競爭中，應是後進者較具有優勢的。

關鍵字

空間競爭；Hotelling 模型；聚集；方向性市場；依序進入；福利

並列摘要

This dissertation includes four essays on spatial competition under various market spaces and various competition strategies of firms. The title of Chapter 2 (first essay) is “Spatial Cournot Competition in a Circular City with Directional Delivery Constraints.” This chapter analyzes spatial Cournot competition in a circular city with a directional delivery constraint, which means that a firm can only deliver its product in one direction. It reveals that, contrary to the standard result, the unique location equilibrium involves duopoly firms agglomerating at the same location when they deliver products in different directions or when the direction decisions are made endogenously. We point out that spatial agglomeration emerges from a central point of view for a firm in a circular city, showing relaxing quantity competition through cost differentiation.
The title of Chapter 3 (second essay) is “A General Analysis of Spatial Cournot Competition and Economic Welfare in Spatially Separated Markets.” This chapter investigates welfare properties in a location-quantity game for spatially separated markets with general demand functions. It is found that maximal location differentiation is not only socially optimal, but it is also the only possible location equilibrium. For a policy implication, this implies that there is no need for government intervention by relocating the firms. The cost asymmetry between firms resulting from location differentiation is both socially and individually preferred in spatially separated markets.
The title of Chapter 4 (third essay) is “A Revisit to Quality Variations and Maximal Variety Differentiation.” Economides (1989) claims to have shown that for a sequential game of variety (or, say, location) choice and subsequent quality and price choice in a Hotelling model with linear transportation costs, there exist only maximal variety differentiation and minimal quality differentiation equilibrium. The primary purpose of this chapter is to show that, in a rigorous manner, no location equilibrium exists in this model. The key factor of the non-existence problem is because no best response of the location choice exists whenever a firm’s opponent locates at the edge of the market in Economides’ (1989) model. This chapter also provides a slightly modified version based on the functional form of the transportation cost and the game structure to overcome the non-existence problem.
The title of Chapter 5 (fourth essay) is “Sequential Location in a Discrete Directional Market with Three or More Players”. This chapter analyzes a three-player sequential entry game in a discrete directional market. It is shown that there are multiple equilibrium outcomes, and any player may take advantage in this game due to the indifference problem of the players. However, if we utilize some further refinements such as the validated equilibrium introduced by Spagat (1992) or lexicographic preference relation players with payoff ranking being the second determinants, the results present that the later the players enter a directional market, the greater the benefits they will receive. This chapter ends with an extension of a general number of players.

並列關鍵字

Spatial competition ； Hotelling model ； Agglomeration ； Directional market ； Sequential entry ； Welfare

參考文獻

de Frutos, M.A., Hamoudi, H., Jarque, X., 1999. Equilibrium existence in the circle model with linear quadratic transport cost. Regional Science and Urban Economics 29, 605-615.

Gupta, B., Lai, F.C., Pal, D., Sarkar, J., Yu, C.M., 2004. Where to locate in a circular city? International Journal of Industrial Organization 22, 759-782.

Irwin, D., Klenow, P., 1994. Learning-by-doing spillovers in the semiconductor industry. Journal of Political Economy 102, 1200-1227.

Matsumura, T., Shimizu, D., 2006. Cournot and Bertrand in shipping models with circular markets. Papers in Regional Science 85, 585-598.

Matsushima, N., 2001. Cournot competition and spatial agglomeration revisited. Economics Letters 73, 175-177.