L’objet de cette thèse est d’analyser comment la politique de la concurrence peut être utilisée pour améliorer le pouvoir d’achat en générant des baisses de prix et affecter la répartition des revenus. L’évaluation des conséquences sur le bien-être de l’entrée de nouveaux concurrents sur un marché a fait l’objet d’une littérature importante. Mais elle repose sur des analyses en équilibre partiel et une approche complémentaire en terme d’équilibre général peut être utile. D’autres analyses de la politique de la concurrence en terme d’équilibre général ont été effectuées pour des économies avec des rendements d’échelle croissants.Cependant, dans la mesure où il semble discutable que les secteurs dans lesquels les rendements d’échelle sont croissants soient majoritaires dans les économies réelles, il apparaît pertinent d’analyser les effets de l’entrée dans des économies "convexes". Nous nous appuyons ainsi sur des modèles simples d’équilibre général pour étudier les conséquences de la politique de la concurrence - en matière d’entrée, de fusions etc... - sur le bien-être. Afin d’analyser ses effets distributifs, nous considérons des économies composées d’agents qui se distinguent par la nature des facteurs qu’ils offrent. Nous supposons en particulier que l’un d’eux fournit une quantité de travail exogène, que nous endogénéisons par la suite. Nous montrons ainsi que la politique de la concurrence peut être conflictuelle : elle peut ne pas impacter tous les consommateurs de la même façon et bénéficier à certains, au détriment d’autres. / This thesis consists in analysing how competition policy by enhancing prices decreases,may be used to boost purchasing power and influence income distribution. A huge literature deals with the evaluation of how entry of firms within a particular sector improves welfare. But this literature mainly relies on a partial equilibrium approach. To complete this approach, a general equilibrium view point on competition policy is called for. There have been several attempts to study the welfare effects of entry in general equilibrium economies with increasing returns to scale. However, it is not clear that pervasive unexploited increasing returns to scale exist in real economies. Therefore, it seems relevant to consider the case of "convex" economies. In this perspective, we use simple general equilibrium models to examine how competition policy - with regard to entry or mergers - affects welfare. In order to study the redistributive effects of competition policy, we consider the case where several agents supply different inputs (the supply of labor is first considered as exogenous,and then endogenous). We show that competition policy is not always welfare improving for all agents.

Une des particularités du marché des compagnies aériennes est la grande divergence des prix des billets pour les mêmes vol. Cela reflète principalement l'incapacité des entreprises à modifier facilement les volumes de production et/ou à les stocker. Le développement et l'utilisation des modèles de "yield management" (modèles d'attribution des sièges) ont été centrés sur les compagnies aériennes proposant différents types de tarifs pour un même vol. L'objectif de cette thèse est de construire un certain nombre de modèles économiques pour expliquer la dispersion des prix sur le marché du transport aérien à partir de différents points de vue. Dans le chapitre 3, je crée un modèle de prix direct qui explique comment différentes caractéristiques du produit et du consommateur influencent le niveau de prix. Le chapitre 4 est consacré aux différences de niveau de prix du point de vue de la concurrence. Dans un jeu stratégique où les entreprises se font concurrence, ! 'ensemble de stratégies rationalisables pour chaque joueur implique toutes les meilleures réponses aux décisions des autres. Ce chapitre propose un test empirique de l'existence de l'équilibre de Nash unique dans un oligopole de Cournot. Dans le chapitre 5, je traite le marché des passagers aériens comme un marché différenciant les produits et applique un modèle logit multinomial pour calculer les élasticités-prix. Le modèle logit (mettant particulièrement l'accent sur l'hétérogénéité des consommateurs) estime de quelle manière les différentes caractéristiques du produit influencent les parts de marché. / Nowadays one of peculiarities of the liberalized airline market is a huge divergence of ticket prices for the same flights. Mostly it reflects the companies' being unable to easily change the volumes of production or/and store them. The development and use of the yield management models (seat allocation models) have centered on airlines offering a variety of different types of fares for travel on the same flight. The goal of this dissertation is to construct a number of economic models to explain the price dispersion on the airline market from the different points of view. In Part 3, I create a direct price mode! which explains how different product and consumer characteristics influence the price level. It is shown how different attributes like the moment of ticket reservation, ticket class, weekday of the departure and number of coupons define the price and how it corresponds to the consumer characteristics (gender, income, age, etc.). Part 4 is devoted to the differences of the price level from the competition point of view. In a strategic game where firms compete against each other the set of rationalizable strategies for each player entails ail the best responses to the others' decisions. This chapter proposes an empirical test of the existence of the unique Nash equilibrium in a Cournot oligopoly. In Part 5 I treat an airline passenger market as a market with the product differentiation and apply a multinomial logit model to calculate price elasticities. The logit model (with a special focus on the consumers heterogeneity) estimates how the different product characteristics influence the market shares.

In this thesis current questions regarding the functionality of liberalized electricity markets are studied addressing different topics of interest in two main directions: market power and competition policy on electricity wholesale markets, and network investments and incentive regulation. The former is studied based on the case of the German electricity market with respect to ex-post market power analysis and ex-ante remedy development. First an optimization model is designed to obtain the competitive benchmark which can be compared to the observed market outcomes between 2004 and 2006. In a second step the horizontal breaking up of dominant firms (divestiture) is simulated applying equilibrium techniques (the classical Cournot approach and the Supply Function Equilibrium approach). The later issue of transmission capacity investment is addressed by highlighting the complexity of network investments in electricity markets and by analyzing a regulatory mechanism with a two part tariff approach. The technical characteristics of power flows are combined with economic criteria and tested for different network settings.

We describe a stochastic network interdiction problem in which an interdictor, subject to limited resources, installs radiation detectors at border checkpoints in a transportation network in order to minimize the probability that a smuggler of nuclear material can traverse the residual network undetected. The problems are stochastic because the smuggler's origin-destination pair, the mass and type of material being smuggled, and the level of shielding are known only through a probability distribution when the detectors are installed. We consider three variants of the problem. The first is a Stackelberg game which assumes that the smuggler chooses a maximum-reliability path through the network with full knowledge of detector locations. The second is a Cournot game in which the interdictor and the smuggler act simultaneously. The third is a "hybrid" game in which only a subset of detector locations is revealed to the smuggler. In the Stackelberg setting, the problem is NP-complete even if the interdictor can only install detectors at border checkpoints of a single country. However, we can compute wait-and-see bounds in polynomial time if the interdictor can only install detectors at border checkpoints of the origin and destination countries. We describe mixed-integer programming formulations and customized branch-and-bound algorithms which exploit this fact, and provide computational results which show that these specialized approaches are substantially faster than more straightforward integer-programming implementations. We also present some special properties of the single-country case and a complexity landscape for this family of problems. The Cournot variant of the problem is potentially challenging as the interdictor must place a probability distribution over an exponentially-sized set of feasible detector deployments. We use the equivalence of optimization and separation to show that the problem is polynomially solvable in the single-country case if the detectors have unit installation costs. We present a row-generation algorithm and a version of the weighted majority algorithm to solve such instances. We use an exact-penalty result to formulate a model in which some detectors are visible to the smuggler and others are not. This may be appropriate to model "decoy" detectors and detector upgrades. / text

在新國際貿易理論的討論中，強調政府應扮演主動積極的角色以提升福利水準，然而這部份的探討大多忽略了廠商的逃漏稅行為。我們不禁要想，在加入廠商逃漏稅後，政府是否仍可扮演其主動積極之角色，採取稽查以降低廠商逃漏稅行為，或藉由調整關稅以降低廠商逃漏稅行為。本文建立一貿易模型，分別以簡單的廠商逃漏稅模型及政府查核的廠商逃漏稅模型做探討，研究結果發現，由於在逃漏稅經濟體系下，利潤稅制仍具有中立性，因此最適關稅決策不會改變；另外，由分析結果知，關稅的存在無法影響本國廠商逃漏稅行為，即貿易自由化無法改善地下經濟規模問題。

One of the main concerns with the introduction of competition in the power sector is the strategic behaviour of market participants. Computable models of strategic behaviour are becoming increasingly important to understand the complexities of competition. Such models can help analyze market designs and regulatory policies. In this thesis, further developments on the modelling and analysis of strategic behaviour in electricity markets are presented. This thesis work has been conducted along three research lines. <br /><br /> In the first research line, an oligopolistic model of a joint energy and spinning reserve market is formulated to analyze imperfect competition. Strategic behaviour is introduced by means of conjectured functions. With this integrated formulation for imperfect competition, the opportunity cost between generation and spinning reserve has been analytically derived. Besides, inter-temporal and energy constraints, and financial transmission rights are taken into account. Under such considerations, competition in electricity markets is modelled with more realism. The oligopolistic model is formulated as an equilibrium problem in terms of complementarity conditions. <br /><br /> In the second research line, a methodology to screen and mitigate the potential exacerbation of market power due to the ownership of financial transmission rights is presented. Hedging position ratios are computed to quantify the hedging level of financial transmission rights. They are based on the actual impact that each participant has in the energy market, and on the potential impact that it would have with the ownership of financial transmission rights. Thus, hedging position ratios are used to identify the potential gambling positions from the transmission rights bidders, and, therefore, used to prioritize critical positions in the auction for transmission rights. <br ><br /> In the last research line, alternative equilibrium models of markets for financial transmission rights are formulated. The proposed equilibrium framework is more natural and flexible for modelling markets than the classic cost-minimization markets. Different markets for financial transmission rights are modelled, namely: i) forwards, ii) options, and iii) joint forwards and options. Moreover, one-period, multi-period and multi-round markets for forwards are derived. These equilibrium models are proposed to analyze the bidding strategies of market participants. The potential impact of bidders on congestion prices is modelled by means of conjectured transmission price functions.

One of the main concerns with the introduction of competition in the power sector is the strategic behaviour of market participants. Computable models of strategic behaviour are becoming increasingly important to understand the complexities of competition. Such models can help analyze market designs and regulatory policies. In this thesis, further developments on the modelling and analysis of strategic behaviour in electricity markets are presented. This thesis work has been conducted along three research lines. <br /><br /> In the first research line, an oligopolistic model of a joint energy and spinning reserve market is formulated to analyze imperfect competition. Strategic behaviour is introduced by means of conjectured functions. With this integrated formulation for imperfect competition, the opportunity cost between generation and spinning reserve has been analytically derived. Besides, inter-temporal and energy constraints, and financial transmission rights are taken into account. Under such considerations, competition in electricity markets is modelled with more realism. The oligopolistic model is formulated as an equilibrium problem in terms of complementarity conditions. <br /><br /> In the second research line, a methodology to screen and mitigate the potential exacerbation of market power due to the ownership of financial transmission rights is presented. Hedging position ratios are computed to quantify the hedging level of financial transmission rights. They are based on the actual impact that each participant has in the energy market, and on the potential impact that it would have with the ownership of financial transmission rights. Thus, hedging position ratios are used to identify the potential gambling positions from the transmission rights bidders, and, therefore, used to prioritize critical positions in the auction for transmission rights. <br ><br /> In the last research line, alternative equilibrium models of markets for financial transmission rights are formulated. The proposed equilibrium framework is more natural and flexible for modelling markets than the classic cost-minimization markets. Different markets for financial transmission rights are modelled, namely: i) forwards, ii) options, and iii) joint forwards and options. Moreover, one-period, multi-period and multi-round markets for forwards are derived. These equilibrium models are proposed to analyze the bidding strategies of market participants. The potential impact of bidders on congestion prices is modelled by means of conjectured transmission price functions.

This dissertation explores several aspects of the theory in industrial organization. The first chapter builds a model with two cost asymmetric firms who not only have Cournot competition in the spot market but also have the opportunity to trade forward contracts. It is shown that with forward trading, low cost firm not always produces more than high cost firm. In an interior equilibrium, both total output and consumer welfare increase compared to the case without forward trading. When cost function is linear, forward trading is socially beneficial in that low cost firm has higher market share as well as profit share, and that total output, consumer welfare and social welfare increase. The second chapter analyzes duopoly firms' choices among ad-free and ad-supported service with different advertising displays: mandatory advertising where ads are integrated with the main content and cannot be dismissed by users; or optional advertising where users are allowed to dismiss ads at will. The model also takes into account the effect of consumers' heterogeneous ad tastes on their contribution to ad revenues. The results reveal that ad revenues intensify competition, suppress equilibrium prices and profits, and diminish the differentiation effect. The third chapter studies firms' business model choices and pricing decisions when they can choose to provide ad-free service, ad-supported service with cost-per-click (CPC) revenue model or cost-per-mille (CPM) revenue model, or a combination of them in monopoly or duopoly environment. It's shown that offering both types of ad-supported services is not an optimal strategy for a monopolist and that its optimal strategy is to vertically differentiate by providing an ad-supported service and an ad-free service. Furthermore, when the monopolist adopts the CPM-based ad revenue model, the price of the ad-supported service is more sensitive to increases in the marginal ad revenue than the case with the CPC-based model. In the equilibrium of competitive setting, exactly one firm offers an ad-supported service alone while the other firm offers the ad-free service with or without the same type of ad-supported service depending on the ad revenues. / text

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Traditionally, time series of wholesale electricity market spot prices have been modelled either by mimicking market operation and equilibrating demand and supply, or by specifying an exogenous process for prices. More recently, a number of hybrid models have been developed, combining the merits of both methods. In this vein, we present an econometric model for daily spot prices in the New Zealand Electricity Market (NZEM) that utilises reservoir management theory to incorporate information on the hydro storage level, a recognised driver of NZEM spot price behaviour. In order to forecast future storage levels and prices, we also construct a model for daily reservoir releases that can be used in conjunction with time series of inflows. This analysis reveals that releases in New Zealand are driven primarily by hydrological factors, as opposed to market conditions. The combined price and storage forecasting model can be applied in a variety of contexts, and offers an alternative perspective to the traditional models of NZEM behaviour. Finally, we calibrate a Cournot model of market behaviour in the National Electricity Market of Australia during daily peak, shoulder and off-peak periods, adding credibility to the future application of such models. The resulting model parameters are, in general, consistent with conventional wisdom. Spot prices from this market are then modelled by combining the output of the analytical model with a stochastic price process.