This thesis is composed of three chapters. Chapter 1 considers the existence of equilibria in games with complete information, where players may have non-ordered and discontinuous preferences. Chapter 2 studies the issues on the existence of pure and behavioral strategy equilibria in games with incomplete information and discontinuous payoffs. We consider the standard setting with Bayesian preferences as well as the case in which players may face ambiguity. Chapter 3 extends the classical results on the Walras-core existence and equivalence to an ambiguous asymmetric information economy, where agents maximize maximin expected utilities (MEU). These results are based on the papers He and Yannelis (2014, 2015a,b,c, 2016a,b). In the first chapter, we propose the condition of "continuous inclusion property" to handle the difficulty of discontinuous payoffs in various general equilibrium and game theory models. Such discontinuities arise naturally in economic situations, including auction, price competition of firms and also patent races. Based on the continuous inclusion property, we establish the equilibrium existence result in a very general framework with discontinuous payoffs. On one hand, this condition is sufficiently general from the methodological point of view, as it unifies almost all special conditions proposed in the literature. On the other hand, our condition is also potentially useful from the realistic point of view, as it could be applied to deal with many economic models which cannot be studied before because of the presence of the discontinuity. In the second chapter, I study the existence problem of pure and behavioral strategy equilibria in discontinuous games with incomplete information. The framework of games with incomplete information is standard as in the literature, except for that we allow players' payoffs to be discontinuous. We illustrate by examples that the Bayesian equilibria may not exist in such games and the previous results are not applicable to handle this problem. We propose some general conditions to retain the existence of both pure strategy and behavioral strategy Bayesian equilibrium, and show that our condition is tight. In addition, we study the equilibrium existence problem in discontinuous games under incomplete information and ambiguity, and show that the maximin framework solves the equilibrium existence issue without introducing any additional condition. In the last chapter, I study a general equilibrium model with incomplete information by adopting the maximin expected utilities. The model is powerful enough to describe the behaviors of risk averse agents that cannot be explained by the standard assumption of subjective expected utilities. I use this new formulation to extend many classical results in general equilibrium theory by incorporating ambiguity into the model. In addition, the desirable incentive compatibility property is shown in our model with maximin expected utilities, while this property will typically fail in the traditional setup. Specifically, the existence results are shown for various equilibrium notions in a general equilibrium model, and the incentives can be guaranteed when all agents use the maximin expected utilities.

This dissertation explores how natural ecosystem can be integrated with economic system through two case studies of multiple species interactions, or predator-prey relations. By the inclusion of biological, ecological and economic aspects, the integrated approaches aim at more clearly understanding of how regional ecosystem and economy interact with each other, given threats of resource extinction and environmental shock. I also explain strategies and policy regimes that can be considered to achieve efficient and sustainable ecosystem management in those circumstances. The first case study focuses on a predator-prey relation in the Pacific Ocean between the United States and Canada, where endangered/threatened predators feed primarily on commercially valuable species as prey. Accounting for the importance of those predators as critical natural resources for whale watching industry, this case study synthesizes the species biological and the regional economic systems, and analyzes possible management strategies for both ecosystem conservation and sustainable economic growth. A long-term drought and fragmented management has been one of the critical issues in the Great Salt Lake (GSL) ecosystem that is linked with its regional economy in Utah. For this issue, the second case study builds an integrated model for describing how the lakes main natural resources, such as water, brine shrimp, and migratory birds, are related to primary industries in the region including agriculture, mining, fishery, and recreation. With the model framework, the study presents how the prolonged drought affects both the GSL ecosystem and its rigional economy, and suggests economic management strategies for the lakes ecosystem recovery in the presence of drought.

In this thesis I address several neglected issues relating to the theoretical and applied analysis of human capital and the impact of taxation. I begin with the problem of measuring the effective tax rate on human capital accumulation. I develop a forward-looking measure of the effective tax rate that is grounded in human capital theory, allowing for features that differentiate human capital formation from physical capital formation. These features include concavity of the earnings-investment frontier and adjustments in capital utilization through leisure. I argue that the few attempts that have been made to measure the effective tax rate on skill formation are either limited by the fact that they inherit assumptions applicable to the theory of the firm or have dubious theoretical foundations (Chapter Two). The new measure is used to derive the effective tax rate on human capital in 25 OECD countries, including Australia (Chapter Three). While there are numerous general equilibrium models which integrate nominal rigidities of one form or another, little attention has been devoted to nominal rigidities arising from partial indexation of income tax thresholds. No doubt one of the reasons for this gap in the literature is the difficulty associated with introducing a fully specified progressive tax regime into an applied general equilibrium model. I show that this hurdle can be overcome through a zero-profit condition for general equilibrium on the labour market. The condition is integrated into an aggregative model of the economy consisting of two sectors (consumption and education) and two factors of production (skilled and unskilled labour). Since skill formation is endogenous, the model allows us to reopen research into the optimal level of skill formation and the role of government (Chapter Four). An applied general equilibrium version of the model is used to evaluate the impact of recent tax reform proposals on skill formation (Chapter Five). A concluding chapter draws together these lines of enquiry with suggestions for future research (Chapter Six).

This paper investigates the potential for a carbon tax to induce R&D, and for the consequent induced technical change (ITC) to lower the macroeconomic cost of abating carbon emissions. ITC is modelled within a general equilibrium simulation of the U.S. economy by the effects of emissions restrictions on the level and composition of aggregate R&D, the accumulation of the stock of knowledge, and the industry-level reallocation and substitution of intangible services derived therefrom. Contrary to other authors, I find that ITC's impact is large, positive and dominated by the latter "substitution effect," which mitigates most of the deadweight loss of the tax. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / This research was supported by the Offce of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-02ER63484, and by funding from the MIT Joint Program on the Science and Policy of Global Change, which is supported by a consortium of government, industry and foundation sponsors.

Essay one develops and tests a revenue-maximizing tax structure model. This model represents one of the first attempts to evaluate and compare the responsiveness of various tax instruments to tax evasion within a tax revenue maximization framework. We use data from both the OECD and East African countries and estimation is via a seemingly unrelated regression model. The GDP share of agricultural income is used as an instrument to correct for the simultaneity between tax revenue shares and tax evasion. Our findings indicate that tax evasion increases the tax authority’s reliance on consumption taxes vis-à-vis taxes on income, suggesting that diverse tax instruments respond differently to tax evasion, and as such the choice of a revenue-maximizing tax structure is influenced by the amount of revenue lost through tax evasion. Essay two analyzes the incidence of tax evasion in both the formal and informal sectors of the economy using a computable general equilibrium model. This essay incorporates the element of uncertainty in an individual’s decision to evade so as to account for the uncertainty of returns to the tax evader. We also allow for varying degrees of competi¬tion or entry across sectors in the economy to examine how much of the tax advantage is retained by the initial evaders and how much is shifted via factor and commodity price changes. Our simulation results show that the evading households’ post-evasion welfare is only 0.68-3.40 percent higher than the post-tax welfare if it had fully complied with taxes. The simulation results further reveal that the evading household keeps 77.1-83.2 percent of this initial increase in welfare, while 16.8-22.9 percent of this initial gain is competed away as a result of increased competition and entry into the informal sector. The compliant households’ welfare increases by 58.8-101.7 percent with increased competition in the informal sector. Therefore, if we construe the changes in consumer welfare as an overall indicator of the gains and/or losses from tax evasion, then the evading household only benefits marginally and this advantage diminishes with increased entry or competition in the informal sector.

This thesis extends the literature on trade-linked international environmental policy by quantifying the effects of collective taxes on polluting intermediate inputs under varying trade, market structure and labour market assumptions. Using a CGE model augmented to include emissions from intermediate inputs, I simulate the effects of coordinated and harmonized environmental taxes on output, trade, and market structure. The main objectives are to ascertain whether free trade improves regulatory policy outcomes, and to demonstrate how market structure and the relative size of trading partners affect policy responses. To this end, I consider three cases: (a) asymmetric regions competing under perfect competition (b) asymmetric regions competing under imperfect competition and (c) symmetric regions competing under imperfect competition. Using Canada-EU and NAFTA-EU trade to represent asymmetric and symmetric trade ties, the results reveal the following: When regions are asymmetric, free trade unambiguously improves regulatory outcomes for the EU, but yields mixed results for Canada. In addition, regulatory costs are lower when trading partners are symmetric. However, free trade can result in perverse outcomes. For asymmetric regions, output and market structure changes are stronger under imperfect competition, and in the presence of real wage unemployment. Results also suggest that aggregate trade flows are not very sensitive to environmental taxes but are sensitive to changes in border taxes. Finally, welfare effects do not follow a predictable pattern because they partly depend on market structure changes.

Despite the prevalence of computable general equilibrium (CGE) models applied to tax changes of varying types, little work has been done focusing on state level comprehensive tax reform or on tax reform in countries undergoing a regime change. This research develops and applies methodologies for analyzing fiscal policy changes under these two very different economic scenarios. The findings for each application are relevant to policy makers as they weigh the effects of tax reform. The models developed for the two scenarios offer guidance to future modelers in studying similar economies and the contrast of the two provides a framework for thinking about model design and application. Finally, the results, when compared to each other, allow us to see the relative effectiveness of the two tax reform policies given their very different economies.

In this thesis I address several neglected issues relating to the theoretical and applied analysis of human capital and the impact of taxation. I begin with the problem of measuring the effective tax rate on human capital accumulation. I develop a forward-looking measure of the effective tax rate that is grounded in human capital theory, allowing for features that differentiate human capital formation from physical capital formation. These features include concavity of the earnings-investment frontier and adjustments in capital utilization through leisure. I argue that the few attempts that have been made to measure the effective tax rate on skill formation are either limited by the fact that they inherit assumptions applicable to the theory of the firm or have dubious theoretical foundations (Chapter Two). The new measure is used to derive the effective tax rate on human capital in 25 OECD countries, including Australia (Chapter Three). While there are numerous general equilibrium models which integrate nominal rigidities of one form or another, little attention has been devoted to nominal rigidities arising from partial indexation of income tax thresholds. No doubt one of the reasons for this gap in the literature is the difficulty associated with introducing a fully specified progressive tax regime into an applied general equilibrium model. I show that this hurdle can be overcome through a zero-profit condition for general equilibrium on the labour market. The condition is integrated into an aggregative model of the economy consisting of two sectors (consumption and education) and two factors of production (skilled and unskilled labour). Since skill formation is endogenous, the model allows us to reopen research into the optimal level of skill formation and the role of government (Chapter Four). An applied general equilibrium version of the model is used to evaluate the impact of recent tax reform proposals on skill formation (Chapter Five). A concluding chapter draws together these lines of enquiry with suggestions for future research (Chapter Six).

The purpose of this thesis is to assess the effects of China???s growth, investment in higher education and trade liberalisation on China and its neighbouring East Asian economies. The study is conducted within the framework of a dynamic multi-sector, multi-region computational general equilibrium model, which incorporates endogenous capital and skill accumulation. China???s trade liberalisation induces substantial investment spending and accumulation of capital and skilled labour in China and East Asia. There is a positive wage outcome for skilled and unskilled labour in both regions. The expanded trade opportunities with China should compensate East Asia for the loss of exports to the rest of the world. Complementarity exists between the exports of China and East Asia with East Asia supplying China???s skill-intensive manufacturing sectors with components and parts which are then used as inputs into China???s exports. Furthermore, the simulation results indicate that China???s trade reforms will support the industrial upgrading process in China but the impact is more apparent in the long term. As China transforms into a more skill oriented, open and competitive economy, it will impose significant structural adjustments on itself and East Asia. A large increase in the output and exports of low tech manufacturing is seen in China, as well as in the high skill sectors of intermediate manufacturing, durables and traded services. China???s exports and imports surge, further rising its presence in the global trading system. The exports of East Asia to the rest of the world decline across the sectors except for the durables sector. However, the decline in the exports of several sectors in East Asia to the rest of the world was offset by the increase in the exports of these sectors to China.

O objetivo principal deste trabalho é analisar as interações econômicas das unidades da Federação. Cabe ressaltar que as interações serão tratadas neste trabalho como o comércio entre as diversas unidades espaciais e suas relações mercantis com o resto do mundo. Para atingir tal objetivo foi especificado um modelo de equilíbrio geral computável de tradição australiana (B-MARIA27-IT). O modelo é composto por seis tipos de agentes, quais sejam: setores produtivos, investidores, famílias, governo federal, governo regional e setor externo. Em cada uma das 27 regiões contempladas há oito setores produzindo oito bens. O setor externo é dividido em cinco blocos de comércio: NAFTA, resto da ALCA, União Européia, Mercosul e resto do mundo. Para analisar a estrutura de interações econômicas entre as unidades da Federação foi implementado um exercício de simulação, que consistiu em um deslocamento na curva de demanda por exportações para os diversos blocos de comércio, ou seja, uma proxy do fortalecimento das interações destas unidades com determinado bloco de comércio. Através deste exercício pode-se verificar, por exemplo, qual o impacto de um aumento das transações internacionais de um setor localizado em determinada unidade da Federação, sobre os fluxos de comércio interno das demais unidades da Federação. Ao fazer esta análise através de um modelo de equilíbrio geral computável (EGC) pode-se levar em conta a possibilidade de substituição entre bens domésticos e importados, a variação nos preços relativos, a possibilidade de substituição diferenciada para os bens de exportação, dentre outros. Cabe ainda ressaltar que, para analisar a interdependência entre setores, regiões e famílias de forma mais acurada, é importante levar em conta, por exemplo, diferenciais de preço e mobilidade dos fatores de produção, dentre outros fatores. Logo, a estrutura de EGC parece-nos mais adequada para tratar, de forma completa, as interações espaciais entre as unidades da Federação. / The principal aim of this thesis is to analize the economic interactions among the Brazilian states. The economic interactions in this work will be treated as trade among the Brazilian states and trade between the Brazilian states and the rest of the world. In order to reach this objective a computable general equilibrium model was specified (B-MARIA27-IT). The model is formed by productive sectors, investors, households, federal government, regional government and external sector. There are 8 sectors responsible for the production of 8 goods in each one of the 27 regions. The external sector is divided in five regions: NAFTA, rest of FTAA, European Union, Mercosur and rest of the world. In order to analise the structure of economic interactions among the Brazilian states was implemented a simulation that changed the exports demand for each one of the external regions. This simulatin can be understand as a proxy of an increase in the relationship between the Brazilian states and external sector. This exercise will enable us to verify which will be the impact upon the inter-state trade flows of an increase in the international trade flows of each Brazilian state. The general equilibrium approach considers the possibility of substitution between domestic goods and imported goods, changes in the relative prices, imperfect substitution among goods, factor production mobility, etc. So we can affirm that the general equilibrium approach is adequate to capture the whole picture of spatial interacions of the Brazilian states.