Dynamic Analysis of Policy Effects in Monopolistically Competitive Economies

本课题的研究成果可以总结如下：1.研究成果。不完全市场下动态经济体的不确定性和复杂行为：为了阐明动态垄断竞争经济体中的政策效应，我首先尝试研究不完全市场经济体的动态行为。在文章#2和#4（见参考文献）中，我推导了在有或没有社会收益增加的内生增长的两个部门模型中均衡不确定性成立的条件。这些论文表明，社会增长的存在，被认为是产生不确定性的必要条件，可能不需要在两部门模型中保持不确定性。在文章#3中，我探讨了增长模型中均衡不确定性的一些经济含义。不完全竞争动态经济中的最优政策。基于上述研究成果，我考察了在不完全竞争的动态经济体中，各种政策效应。第1篇研究了具有研发投资的内生增长经济下的最优专利政策。我（与合著者Koichi Futagami和Ysushi Ohkusa）证明了存在一个有限的、福利最大化的专利长度，因此从社会福利的角度来看，无限制的专利保护可能是有害的。在文章#6中，我研究了收益递增情况下的动态最优税收。本研究的主要结果表明，资本所得税在稳定状态下应该是负的。然而，研究也表明，这一结论对财政当局采用的政策规则（即开环与反馈）很敏感。最后，第5条研究了货币供应政策在重叠一代经济中的增长和福利效应。我（及其合著者柴田昭久）分析了帕拉托在替代政策规则下改善货币政策的存在。本文还证明了在政府预算约束下货币增长是内生决定的情况下，均衡可能存在不确定性。少

The results obtained in this research project may be summarized as follows :1.Indeterminacy and complex behavior of the dynamic economies with imperfect markets :In order to clarify the policy effects in dynamic, monopolistically competitive economies, I have first tried to investigate the dynamic behavior of economies with imperfect markets. In Articles #2 and #4 (see REFERENCES), I derive the conditions under which indeterminacy of equilibrium holds in two sector models of endogenous growth with or without social increasing returns. These papers demonstrate that the presence of social increasing, which has been considered a necessary condition for generating indeterminacy, may not be required to hold indeterminacy in two-sector models.In Article #3, I explored some economic implications of indeterminacy of equilibrium in growth models.2.Optimal policies in dynamic economies with imperfect competition.Based on research results mentioned above, I have inspected various policy effects i … More n dynamic economies with imperfect competition. Article #1 investigated the optimal patent policy in an endogenously growing economy with R&D investment. I (with co-authors, Koichi Futagami and Ysushi Ohkusa) demonstrated that there exists a finite, welfare maximizing patent length so that unlimited patent protection may be harmful from the social welfare viewpoint. In Article #6, I studied the dynamic optimal taxation under increasing returns. The main results of this study show that capital income taxation should be negative in the steady state. However, it is also shown that this conclusion is sensitive to the policy rule (i.e. open-loop vs. feedback) adopted by the fiscal authority.Finally, Article #5 studies growth and welfare effects of money supply policy in an overlapping generation's economy. I (and co-author, Akihisa Shibata) analyzed the presence of Parato improving monetary policy under alternative policy rules. This paper also demonstrated that indeterminacy of equilibria might exist if money growth is endogenously determined according to the government budget constraint. Less