公共維修支出與不完全競爭
　 摘 要
政府往往必須在建造新的公共建設與增加公共建設的維修支出之間進行抉擇。 現今所做的維修不只有助於目前的產出，而且也有助於往後幾年產出的增加。 此外,由於近年來不完全競爭已成為總體經濟學的重要議題之一。 相較於既存的文獻，本文建構了一個中間財部門為獨占性競爭的一般均衡內生成長模型，以探討最適財政政策。
本文的第二章建構一個公共資本與私人資本存量進入生產函數的兩部門內生成長模型。 而且，我們假設公共維修支出既可以增加公共資本的耐久性，又可以提高公共建設的效率。 此外，我們也考慮到維修支出對私人資本折舊率的影響。 文中我們指出成長率極大的稅率與成長率極大的公共維修支出比率會受到不完全競爭的程度所影響。 然而，當私人資本折舊率為外生時，成長極大的稅率與公共維修支出比率則與不完全競爭的程度無關。
第三章我們仍然考慮中間財部門不完全競爭的情況， 假設「公共資本的折舊率」與「維修支出占總產出的比率」呈現負向線性相關。 與第二章不同的是第三章特別強調勞動的內生化。 此外，我們除了討論穩定均衡的成長率極大的稅率之外還討論社會福利極大的稅率。 經由我們給定的資料模擬結果得到：社會福利極大的稅率會小於成長率極大的稅率。

Public Spending on Maintenance and Imperfect Competition
Abstract
The government faces an option between building ‘new’ infrastructure and increasing maintenance expenditure. The maintenance work done in the present is not only a contribution to current final output, but also to the final output of future years. On the other hand, in the recent years, imperfect competition has become a central element of macroeconomics. In contrast to the existing literature, we construct a general equilibrium endogenous growth model with monopolistic competition in the intermediate-goods sector to as we discuss the optimal fiscal policy.
In Chapter 2, we develop an infrastructure-led two-sector endogenous growth model in which public and private capital stocks are entered directly into the production function. Moreover, we assume that maintenance spending by the public sector not only increases the durability of public capital, but also raises the efficiency of the infrastructure. In addition, we also discuss the impact of maintenance spending on the private capital stock. We show that the growth-maximizing tax rate and the share of public maintenance spending may be also affected by the mark-up. However, when private depreciation is exogenous, the growth-maximizing tax rate and the share of maintenance spending are irrelevant to the degree of monopoly power.
In Chapter 3, we also consider an endogenous growth model with monopolistic competition in the intermediate-goods sector. We assume that the depreciation rate of public capital in infrastructure depends negatively on and is linearly related to the ratio of maintenance spending to the economic output. In a departure from the model in Chapter 2, we emphasize the role of endogenous labor utilization in the growth model. Moreover, in this chapter we discuss the steady-state growth-maximizing tax rate as well as welfare-maximizing tax rate of the economy. The welfare-maximizing tax rate is less than the growth-maximizing tax rate for a mildly conservative simulation based on our given parameter values.

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