京都大学 / 0048 / 新制・課程博士 / 博士(経済学) / 甲第21523号 / 経博第591号 / 新制||経||288(附属図書館) / 京都大学大学院経済学研究科経済学専攻 / (主査)教授 梶井 厚志, 教授 原 千秋, 教授 若井 克俊 / 学位規則第4条第1項該当 / Doctor of Economics / Kyoto University / DFAM

The livestock industry in the United States has experienced significant concentration and vertical integration in recent years. This change has resulted in greater observed levels of pollution attributed to concentrated animal feeding operations (CAFO) and society has attempted to use regulation to remedy these problems. Despite regulation at the federal and local level no documented improvement in water quality has been observed to date. This thesis is concerned with the response of profit-maximizing economic agents to the form of environmental regulation adopted at the federal level. A theoretical model of firm profit is proposed and analyzed using comparative statics to derive a variety of firm and policy relevant results. A qualitative discussion of monitoring and enforcement aspects of regulation and transaction costs in public policy implementation is provided. Results suggest that the form that regulation has taken fails to address the economic decision making process of the firm and thus fails to create incentives for more environmentally benign behavior.

Cette thèse se trouve à l'intersection de deux sujets de recherches en économie qui ont connus des développements récents : d'un côté, la modélisation et l'étude des réseaux économiques, de l'autre, la théorie du transport et ses applications en économie. Les quatre chapitres de cette thèse déclinent plusieurs résultats théoriques en lien avec ces deux sujets, en insistant sur leurs connections. Le premier chapitre modélise des contrats bipartites sur un marché décentralisé comme un problème de flux. Ce travail prouve l’existence d'un équilibre compétitif et discute son efficacité. Nous présentons des interprétations de ce modèle dans le cas où les biens sont indivisibles. Ces spécifications sont utilisées pour proposer un modèle du marché du prêt interbancaire. Dans le second chapitre, co-écrit avec Alfred Galichon et Larry Samuelson, nous prouvons un théorème de statiques comparatives monotones. Nous appliquons ensuite ce résultat à plusieurs modèles économiques classiques (modèles d'appariement, modèles hédoniques et problèmes de flux de coût minimum). Le troisième chapitre, co-écrit avec Alfred Galichon et Arthur Charpentier, présente des outils pour résoudre les problèmes d'appariement sur des réseaux de grandes dimensions avant de les mettre en pratique. Enfin le quatrième chapitre, co-écrit avec Rakesh Vohra, montre comment un assureur monopolistique peut utiliser les externalités entre agents - modélisées comme un réseau - pour maximiser ses revenus. Bien qu’exerçant le niveau d'effort optimal d'un point de vue social, tous les agents préfèrent l'équilibre précédant l'introduction de l'assureur. / This dissertation lies at the intersection of two fields of research in economics that have recently substantially developed: on the one hand, the modeling and study of economic networks, and on the other hand, transport theory and its applications in economics. The four chapters of this dissertation present theoretical results in relation with these two topics and put stress on their connections. The first chapter models bipartite contracts on a decentralized market as an equilibrium flow problem. We prove the existence of a competitive equilibrium outcome and discuss its effciency. We interpret this equilibrium in the case of indivisible commodities. As an illustration, we build a model for the overnight interbank loan market with counterparty risk and collateralization costs. In the second one, written in collaboration with Alfred Galichon and Larry Samuelson, we prove a monotone comparative statics theorem that we then apply to several classical economic models (matching models, min-cost flow problems and hedonic models). The third chapter is a joint work with Alfred Galichon and Arthur Charpentier. It presents tools to solve for matching problems on large geographic networks before applying them to examples. Finally, the fourth chapter, written with Rakesh Vohra, shows how a monopolistic insurer can use externalities between agents - modeled as a network - to maximize his profit. We show that a monopolistic insurer decreases the welfare of all agents.

We propose a novel analytic approach for the comparative statics analysis of operations management problems on the capacity investment decision and the influenza (flu) vaccine composition decision. Our approach involves exploiting the properties of the underlying mathematical models, and linking those properties to the concept of stochastic orders relationship. The use of stochastic orders allows us to establish our main results without restriction to a specific distribution. A major strength of our approach is that it is "scalable," i.e., it applies to capacity investment decision problem with any number of non-independent (i.e., demand or resource sharing) products and resources, and to the influenza vaccine composition problem with any number of candidate strains, without a corresponding increase in computational effort. This is unlike the current approaches commonly used in the operations management literature, which typically involve a parametric analysis followed by the use of the implicit function theorem. Providing a rigorous framework for comparative statics analysis, which can be applied to other problems that are not amenable to traditional parametric analysis, is our main contribution. We demonstrate this approach on two problems: (1) Capacity investment decision, and (2) influenza vaccine composition decision. A comparative statics analysis is integral to the study of these problems, as it allows answers to important questions such as, "does the firm acquire more or less of the different resources available as demand uncertainty increases? does the firm benefit from an increase in demand uncertainty? how does the vaccine composition change as the yield uncertainty increases?" Using our proposed approach, we establish comparative statics results on how the newsvendor's expected profit and optimal capacity decision change with demand risk and demand dependence in multi-product multi-resource newsvendor networks; and how the societal vaccination benefit, the manufacturer's profit, and the vaccine output change with the risk of random yield of strains. / Ph. D.

This thesis contributes to the theoretical work on decision and game theory when decision makers or players perceive ambiguity. The first article introduces a new axiomatic framework for ambiguity aversion and provides axiomatic characterizations for important preference classes that thus far had lacked characterizations. The second article introduces a new axiom called Weak Monotonicity which is shown to play a crucial role in the multiple prior model. It is shown that for many important preference classes, the assumption of monotonic preferences is a consequence of the other axioms and does not have to be assumed. The third article introduces an intuitive definition of perceived ambiguity in the multiple prior model. It is shown that the approach allows an application to games where players perceive strategic ambiguity. A very general equilibrium existence result is given. The modelling capabilities of the approach are highlighted through the analysis of examples. The fourth article applies the model from the previous article to a specific class of games with a lattice-structure. We perform comparative statics on perceived ambiguity and ambiguity attitude. We show that more optimism does not necessarily lead to higher equilibria when players have Alpha-Maxmin preferences. We present necessary and sufficient conditions on the structure of the prior sets for this comparative statics result to hold. The introductory chapter provides the basis of the four articles in this thesis. An overview of axiomatic decision theory, decision-making under ambiguity and ambiguous games is given. It introduces and discusses the most relevant results from the literature.