O Sistema Agroindustrial do Leite (SAG) foi alvo de mudanças institucionais importantes nos últimos anos. Dentre essas mudanças podemos ressaltar a IN51 em 2002 e que mais tarde foi substituída pela IN 62 no ano de 2012. O objetivo da normativa foi de criar parâmetros técnicos de produção, identidade e qualidade do leite tipo A, de regular tecnicamente a identidade e qualidade do leite cru refrigerado, pasteurizado e regular tecnicamente a coleta de leite cru refrigerado e seu transporte a granel. Esse estudo pretende discutir: Quais os impactos das mudanças institucionais nas relações entre produtores rurais e laticínios no SAG do leite no Brasil? Foram utilizados como referênciais três correntes teóricas que se integram entre si. A primeira abordagem, a Nova Economia Institucional (NEI), na vertente macro, analisa o papel das instituições sobre o desempenho econômico tendo como precursor o laureado Nobel Douglass North. Para North (1990), a instituições são as regras do jogo de uma sociedade, enquanto os jogadores são as organizações. As instituições definem os incentivos aos agentes econômicos estabelecendo as condições em que as atividades empresariais possam florescer. Ou seja, as instituições importam para definir o ambiente de negócios. A segunda abordagem, a Organização Industrial (OI) fornece instrumentos para analisar os determinantes da estrutura de mercado, tais como ganhos de escala e escopo ou outros condicionantes de criação de barreiras à entrada. A terceira, a Economia dos Custos de Transação (ECT), permite analisar as escolhas estratégicas a partir dos condicionantes institucionais e de mercado, assim como fornece suporte para responder a questão de pesquisa, qual seja: entender a lógica econômica das mudanças nas estruturas de governança decorrentes das novas regulamentações que afetam o SAG do leite. Com base nas abordagens teóricas foram desenvolvidas duas preposição concorrentes, sobre o impacto na relação entre produtores e processadores. A primeira sob a ótica da ECT propôs que a regulamentação leva à queda da especificidade dos ativos (temporal e locacional) e, portanto relações mais tênues entre os produtores rurais e laticínios deveriam emergir. A segunda propôs o oposto, que a IN leva ao aumento do mercado relevante e, sob a ótica da OI, cresce a necessidade de estratégias dos laticínios de relações mais próximas com o produtor (fidelização). Nas regiões produtoras de leite estudadas (Ponte Nova-Minas Gerais e Castro - Paraná) constatou-se aumento de estratégias de fidelização, com contratos formais de pagamento por qualidade e assistência técnica. / The Milk Agribusiness System (MAS) has been subject of important institutional changes in the past few years. Among these changes, we highlight the IN51 as of 2002, that was later replaced by IN 62 as of 2012. The objective of these change was that of creating normative technical parameters for the production, identity and quality of the A type milk, of technically regulating the identity and quality of refrigerated pasteurized and raw milk, and that of technically regulating the collection of refrigerated raw milk and its transportation in bulk. This study aims to discuss: What are the impacts of institutional changes in the relationship between dairy farmers and dairy regulators in the MAS in Brazil? We have used as benchmark three theoretical approaches that integrate together. The first approach, the New Institutional Economics (NIE), in its macro view, examines the role of institutions on economic performance, having as a precursor the Nobel laureate Douglass North. According to North (1990), institutions are the rules of a society, while the players are the organizations. Institutions define the incentives given to economic agents, by establishing the conditions in which business activities can flourish. This means that institutions matter to define the business environment. The second approach, the Industrial Organization (IO), provides tools to analyze the determinants of market structure, such as economies of scale and scope or other constraints; to create entry barriers. The third, Transaction Cost Economics (TCE) allows for the analysis of strategic choices out of the institutional and market constraints, as well as provides support to answer the research question, which is: understanding the economic logic of the governance shifts arising from the new regulations affecting the MAS. Based on these theoretical approaches, two competing hypotheses about the impact on the relationship between producers and processors have been developed. The first, in the perspective of TCE, proposed that regulation leads to lower asset specificity (temporal and locational) and therefore, more tenuous relations between farmers and dairy producers should emerge. The second proposed the opposite, that IO leads to an increase in the relevant market and, from the perspective of IO, a growth in the need for forthcoming strategies between processors and producers (loyalty relationship). In the milk-producing regions studied (Ponte Nova Minas Gerais and Castro - Paraná) we have found and increase in loyalty strategies, with formal contracts of payment in exchange for quality and service.

O marco inicial da proposta de estudo é o Protocolo de Defesa da Concorrência no Mercosul Protocolo de Fortaleza, de 17/12/1996, que apesar de ter sido ratificado por alguns Estados-Parte do Mercosul, e no Brasil tendo sido ratificado por meio do Decreto nº 3.602, de 18/9/2000, pouquíssimo avanço foi identificado em muitos anos de vigência, seja por divergências políticas, seja por dificuldades de implantação, e ainda, por questões de conjuntura, em função de crises econômicas mundiais. A busca por formas de equilíbrio nas relações econômicas ao redor do globo, e seus impactos regionais na América Latina, é constante nos fóruns e organizações internacionais, inclusive envolvendo a repressão ao abuso do poder econômico e a defesa da concorrência, considerando esta um elemento importante para o desenvolvimento dos países da região. O estudo verificou a importância para análises que envolvem temas concorrenciais, por ser efetivamente a sua base e o ponto de partida, a questão da delimitação do mercado relevante. A pesquisa tratou de verificar a centralidade do tema na análise antitruste e a relevância do debate do direito da concorrência para a integração regional, focando especificamente o Mercosul e sua forma de regulação. A integração regional é um processo importante em face das desigualdades mundiais, e pode contribuir para uma melhor eficiência de negociações multilaterais em escala mundial, tornando, assim, útil e necessário o controle internacional do comércio, de forma a buscar o equilíbrio nas relações econômicas com o auxílio da defesa da concorrência. A relevância do tema é destacada pela transposição de fronteiras pelas atividades empresariais, levando também ao transbordamento dos limites de atuação dos órgãos nacionais competentes. Isto coloca a análise antitruste em interessante perspectiva, pois no âmbito nacional, a legislação e a atuação dos agentes está restrita às fronteiras dos países, mas na esfera de atuação do bloco econômico regional, a aplicação desta base normativa em função da extraterritorialidade pode e é muitas vezes questionada, no caso de ausência de regulação específica e/ou norma que autorize a cooperação internacional, advinda de uma instituição supranacional, não obstante a hipótese de reconhecimento e aplicação das normas editadas pelo Mercosul como sendo de Direito Comunitário. Assim, pretende-se demonstrar a importância do tema da regulação em matéria antitruste, focando a questão da definição do mercado relevante, especialmente em um bloco econômico regional como o Mercosul. / The initial mark of the proposed study here is Protocolo de Defesa da Concorrência no Mercosul Protocolo de Fortaleza (\"Competitor\'s Defense Protocol in Mercosul-Protocol of Fortaleza), as of Dec 17th, 1996, that despite being ratified by some States in Mercosul, and being validated in Brazil through Decret number 3.602 as of Sep 18th, 2000, very small advance has been identified in many years, for political reasons or difficulties in implementation, or also, for combination of factors of global economic crisis reasons. The search for a balance in economic relations around the Globe, and its regional impacts in Latin America, is common in foruns and international organizations, inclusively with repression to economic power abuse and the defense of the competition, considering this, an important element for the development of the region. In our study, we verify the importance for analysis involving competitors, because it is a starting point, the question of the relevant market limits. The search has verified how central this theme is in the anti-trust analysis and relevance of the debate about rights in competition for regional integration, focusing on Mercosul and its form of regulation. The regional integration is an important process in face of the global economic differences, and may contribute to a better efficiency of multilateral negotiation in global scale, becoming useful and necessary the international business control, in order to balance economic relations with competitors support. The relevance of the theme is revealed through frontiers transposition and business activities, leading to trespassing limits of international regulators. This statement puts the antitrust analysis in perspective, since national wide, the legislation and the agents reaction is restricted to the frontiers of the country, but on the sphere of the regional economic group, this legislation outside the territory may be and it is indeed usually, questioned, in case of the lack of specific regulation or norm, authorizing international cooperation from supra national institution, not disconsidering the hypothesis of recognition and application of norms edited by Mercosul as Common Law. This way, we intend to demonstrate the importance of the regulation theme in the anti trust scenario, focusing the question of a relevant market definition, specially in a regional economic group such as Mercosul.

This dissertation aims to contribute to the field of economics of competition policy by analyzing the demand structure and the market power in the Turkish beverage industry and in the cola market in particular. First, a demand system for the beverage products has been estimated by using a multi-stage linearized Almost Ideal Demand System (AIDS). Using the own-price elasticity of cola in a SSNIP test (Small but Significant Non-Transitory Increase in Price), it is shown that cola market consists of a distinct relevant product market. Then, the demand elasticities of cola products at brand and package level have been estimated by the simple and nested logit models. Finally, the estimated demand elasticities of cola products have been used in measuring the degree of market power and predicting the effects of a hypothetical merger between Pepsi and Cola Turca by using a merger simulation technique. The results show that all cola suppliers have large price-cost margins for most of their products. Prices of the merging parties increase in average by 15 - 21% after the merger. The merger also causes the market price to increase by 16- 22% and consumer surplus to decrease by nearly 5% in average. Finally, depending on these results, the thesis recommends a stricter merger control criterion than dominance criterion for competition policy in Turkey.

It is important to control whether dominant companies in particular market sectors follow laws and rules and do not abuse their dominance at the expense of weaker companies. This behaviour is likely to damage current or avoid the entry of new competitors, shrink the competition and set the environment for price changes the consumer is exposed to. The thesis clarifies the theoretical aspect of this issue and tries to apply it on the real case from the railway transport sector in order to describe the procedure of defining relevant market and market share and investigating the abusive behaviour. A questionnaire survey among railway passeners is an integral part of the thesis. JEL Classification D21, D22, K21, L11, L12, L40 Keywords Predatory prices, relevant market, SSNIP test, railway transport, Czech Railways Author's e-mail Iva-Slamova@seznam.cz Supervisor's e-mail vacek@fsv.cuni.cz

O marco inicial da proposta de estudo é o Protocolo de Defesa da Concorrência no Mercosul Protocolo de Fortaleza, de 17/12/1996, que apesar de ter sido ratificado por alguns Estados-Parte do Mercosul, e no Brasil tendo sido ratificado por meio do Decreto nº 3.602, de 18/9/2000, pouquíssimo avanço foi identificado em muitos anos de vigência, seja por divergências políticas, seja por dificuldades de implantação, e ainda, por questões de conjuntura, em função de crises econômicas mundiais. A busca por formas de equilíbrio nas relações econômicas ao redor do globo, e seus impactos regionais na América Latina, é constante nos fóruns e organizações internacionais, inclusive envolvendo a repressão ao abuso do poder econômico e a defesa da concorrência, considerando esta um elemento importante para o desenvolvimento dos países da região. O estudo verificou a importância para análises que envolvem temas concorrenciais, por ser efetivamente a sua base e o ponto de partida, a questão da delimitação do mercado relevante. A pesquisa tratou de verificar a centralidade do tema na análise antitruste e a relevância do debate do direito da concorrência para a integração regional, focando especificamente o Mercosul e sua forma de regulação. A integração regional é um processo importante em face das desigualdades mundiais, e pode contribuir para uma melhor eficiência de negociações multilaterais em escala mundial, tornando, assim, útil e necessário o controle internacional do comércio, de forma a buscar o equilíbrio nas relações econômicas com o auxílio da defesa da concorrência. A relevância do tema é destacada pela transposição de fronteiras pelas atividades empresariais, levando também ao transbordamento dos limites de atuação dos órgãos nacionais competentes. Isto coloca a análise antitruste em interessante perspectiva, pois no âmbito nacional, a legislação e a atuação dos agentes está restrita às fronteiras dos países, mas na esfera de atuação do bloco econômico regional, a aplicação desta base normativa em função da extraterritorialidade pode e é muitas vezes questionada, no caso de ausência de regulação específica e/ou norma que autorize a cooperação internacional, advinda de uma instituição supranacional, não obstante a hipótese de reconhecimento e aplicação das normas editadas pelo Mercosul como sendo de Direito Comunitário. Assim, pretende-se demonstrar a importância do tema da regulação em matéria antitruste, focando a questão da definição do mercado relevante, especialmente em um bloco econômico regional como o Mercosul. / The initial mark of the proposed study here is Protocolo de Defesa da Concorrência no Mercosul Protocolo de Fortaleza (\"Competitor\'s Defense Protocol in Mercosul-Protocol of Fortaleza), as of Dec 17th, 1996, that despite being ratified by some States in Mercosul, and being validated in Brazil through Decret number 3.602 as of Sep 18th, 2000, very small advance has been identified in many years, for political reasons or difficulties in implementation, or also, for combination of factors of global economic crisis reasons. The search for a balance in economic relations around the Globe, and its regional impacts in Latin America, is common in foruns and international organizations, inclusively with repression to economic power abuse and the defense of the competition, considering this, an important element for the development of the region. In our study, we verify the importance for analysis involving competitors, because it is a starting point, the question of the relevant market limits. The search has verified how central this theme is in the anti-trust analysis and relevance of the debate about rights in competition for regional integration, focusing on Mercosul and its form of regulation. The regional integration is an important process in face of the global economic differences, and may contribute to a better efficiency of multilateral negotiation in global scale, becoming useful and necessary the international business control, in order to balance economic relations with competitors support. The relevance of the theme is revealed through frontiers transposition and business activities, leading to trespassing limits of international regulators. This statement puts the antitrust analysis in perspective, since national wide, the legislation and the agents reaction is restricted to the frontiers of the country, but on the sphere of the regional economic group, this legislation outside the territory may be and it is indeed usually, questioned, in case of the lack of specific regulation or norm, authorizing international cooperation from supra national institution, not disconsidering the hypothesis of recognition and application of norms edited by Mercosul as Common Law. This way, we intend to demonstrate the importance of the regulation theme in the anti trust scenario, focusing the question of a relevant market definition, specially in a regional economic group such as Mercosul.

O Sistema Agroindustrial do Leite (SAG) foi alvo de mudanças institucionais importantes nos últimos anos. Dentre essas mudanças podemos ressaltar a IN51 em 2002 e que mais tarde foi substituída pela IN 62 no ano de 2012. O objetivo da normativa foi de criar parâmetros técnicos de produção, identidade e qualidade do leite tipo A, de regular tecnicamente a identidade e qualidade do leite cru refrigerado, pasteurizado e regular tecnicamente a coleta de leite cru refrigerado e seu transporte a granel. Esse estudo pretende discutir: Quais os impactos das mudanças institucionais nas relações entre produtores rurais e laticínios no SAG do leite no Brasil? Foram utilizados como referênciais três correntes teóricas que se integram entre si. A primeira abordagem, a Nova Economia Institucional (NEI), na vertente macro, analisa o papel das instituições sobre o desempenho econômico tendo como precursor o laureado Nobel Douglass North. Para North (1990), a instituições são as regras do jogo de uma sociedade, enquanto os jogadores são as organizações. As instituições definem os incentivos aos agentes econômicos estabelecendo as condições em que as atividades empresariais possam florescer. Ou seja, as instituições importam para definir o ambiente de negócios. A segunda abordagem, a Organização Industrial (OI) fornece instrumentos para analisar os determinantes da estrutura de mercado, tais como ganhos de escala e escopo ou outros condicionantes de criação de barreiras à entrada. A terceira, a Economia dos Custos de Transação (ECT), permite analisar as escolhas estratégicas a partir dos condicionantes institucionais e de mercado, assim como fornece suporte para responder a questão de pesquisa, qual seja: entender a lógica econômica das mudanças nas estruturas de governança decorrentes das novas regulamentações que afetam o SAG do leite. Com base nas abordagens teóricas foram desenvolvidas duas preposição concorrentes, sobre o impacto na relação entre produtores e processadores. A primeira sob a ótica da ECT propôs que a regulamentação leva à queda da especificidade dos ativos (temporal e locacional) e, portanto relações mais tênues entre os produtores rurais e laticínios deveriam emergir. A segunda propôs o oposto, que a IN leva ao aumento do mercado relevante e, sob a ótica da OI, cresce a necessidade de estratégias dos laticínios de relações mais próximas com o produtor (fidelização). Nas regiões produtoras de leite estudadas (Ponte Nova-Minas Gerais e Castro - Paraná) constatou-se aumento de estratégias de fidelização, com contratos formais de pagamento por qualidade e assistência técnica. / The Milk Agribusiness System (MAS) has been subject of important institutional changes in the past few years. Among these changes, we highlight the IN51 as of 2002, that was later replaced by IN 62 as of 2012. The objective of these change was that of creating normative technical parameters for the production, identity and quality of the A type milk, of technically regulating the identity and quality of refrigerated pasteurized and raw milk, and that of technically regulating the collection of refrigerated raw milk and its transportation in bulk. This study aims to discuss: What are the impacts of institutional changes in the relationship between dairy farmers and dairy regulators in the MAS in Brazil? We have used as benchmark three theoretical approaches that integrate together. The first approach, the New Institutional Economics (NIE), in its macro view, examines the role of institutions on economic performance, having as a precursor the Nobel laureate Douglass North. According to North (1990), institutions are the rules of a society, while the players are the organizations. Institutions define the incentives given to economic agents, by establishing the conditions in which business activities can flourish. This means that institutions matter to define the business environment. The second approach, the Industrial Organization (IO), provides tools to analyze the determinants of market structure, such as economies of scale and scope or other constraints; to create entry barriers. The third, Transaction Cost Economics (TCE) allows for the analysis of strategic choices out of the institutional and market constraints, as well as provides support to answer the research question, which is: understanding the economic logic of the governance shifts arising from the new regulations affecting the MAS. Based on these theoretical approaches, two competing hypotheses about the impact on the relationship between producers and processors have been developed. The first, in the perspective of TCE, proposed that regulation leads to lower asset specificity (temporal and locational) and therefore, more tenuous relations between farmers and dairy producers should emerge. The second proposed the opposite, that IO leads to an increase in the relevant market and, from the perspective of IO, a growth in the need for forthcoming strategies between processors and producers (loyalty relationship). In the milk-producing regions studied (Ponte Nova Minas Gerais and Castro - Paraná) we have found and increase in loyalty strategies, with formal contracts of payment in exchange for quality and service.

Smyslem práce bylo popsat a kriticky zhodnotit právní úpravu dominantního postavení a s ním úzce spojené vymezení relevantního trhu v prostředí České republiky, Evropské unie a kolébky moderního antitrustového zákonodárství Spojených států amerických. Důraz byl kladen na komparativní analýzu systémů, zejména co se týče vymezení klíčových pojmů a celkového přístupu. Nastíněn byl historický vývoj soutěžního práva se zaměřením na dominantní postavení, jehož určení může mít pro soutěžitele nepříjemné následky a nutnost větší opatrnosti. Následně byly podrobněji představeny úpravy ve vymezených systémech s ohledem na zásadní otázky stanovení dominantního postavení na trhu současně s podrobným představením vymezování relevantního trhu, kde se následně dominance určuje, přes průběžné objasňování a diskutování dalších pojmů v právních předpisech využívaných. Značný prostor byl věnován problematice substituovatelnosti výrobků a služeb, který představoval základní úskalí při vymezování relevantního trhu. Při výkladu bylo pracováno zejména s právními předpisy, klíčovými rozhodnutími soudních orgánů, doplňkovými výkladovými materiály a odbornou literaturou. Práce také částečně hodnotí účelnost a funkčnost úpravy. V praktické části práce byly rozebrány dva vzorové případy Úřadu pro ochranu hospodářské soutěže,...

La libéralisation du transport aérien et maritime a entrainé, à l'instar des autres secteurs, la transformation des infrastructures respectives afin que la libre concurrence soit assurée. Or, à côté des autres conséquences entrainées sur l'exploitation des infrastructures, l'évolution majeure a été le déploiement d'une concurrence entre elles. Malgré les missions particulières de satisfaction de l'intérêt général qui peuvent peser sur les infrastructures de transport et même si chaque infrastructure prise isolément détient un pouvoir de marché considérable, les infrastructures aéroportuaires ou portuaires sont susceptibles de subir une pression concurrentielle. En effet, les caractéristiques de monopole naturel des aéroports et des ports ont été relativisées sous l'effet de la mobilité dans l'économie de transport. Tant les aéroports que les ports deviennent souvent des maillons dans les stratégies concurrentielles des transporteurs, qui constituent leurs interlocuteurs puissants. Le droit a réagi à ce phénomène économique avec le démantèlement des monopoles étatiques, par leur privatisation ou décentralisation, et la restructuration des infrastructures. Par conséquent, il a entrainé une concurrence entre les opérateurs qui ont émergé, qui s'exerce pour et dans le «marché des infrastructures». Il s'agit certainement d'un marché «hétéro-déterminé», c'est à-dire hautement dépendant de la concurrence des transporteurs. D'une part, la délimitation du marché pertinent prend en compte le marché du transport, d'autre part, les formes que peut revêtir la concurrence entre infrastructures ou leur coopération éventuelle sont dictées par les stratégies des transporteurs. / The liberalization of air and maritime transport has resulted in the transformation of the respective infrastructures, in order to facilitate competition between transport operators. However, the most remarkable change has been the development of competition between them. In spite of the particular tasks of general interest assigned to the infrastructures of transport and although each infrastructure taken separately holds a considerable market power, airports and ports are susceptible to competitive pressure. Indeed, the natural monopoly characteristics have been relativized due to the mobility in the economy of transport. Both airports and ports often become simple links in the competitive strategies of carriers, which constitute their powerful counterparts. The law responded to this economic phenomenon, by dismantling state monopolies, proceeding to their privatization or decentralization. Therefore, this tendency has led to a competition between emerged operators, for and within the "market of infrastructures". This market is certainly "hetero-determined", which means that it is highly dependent of the competition in the market of transport. Thus, the definition of the relevant market takes into account the market of transport. Besides, the possible forms of competition or cooperation between infrastructures are determined by the carrier strategies.

Cette thèse regroupe les principaux jalons pour l’analyse concurrentielle des marchés impliquant des activités de réseau et des services ou produits numériques. Le propos s’organise en trois parties qui sont autant d’essais pour rendre compte de l’impact des spécificités de ces marchés sur leur dynamique concurrentielle. La première partie de la thèse porte sur la question de la concentration des plateformes Internet. Un modèle de marché biface est spécifié pour rendre compte des différents niveaux d’interdépendance sur les plateformes mettant en relation entreprises ou annonceurs, d’une part, et audience ou consommateurs, d’autre part. Il en ressort que les effets de réseaux (les synergies et économies d’échelle émanant du nombre d’utilisateurs de la plateforme) sont telles que tout avantage (premier entré sur le marché, qualité ou part d’audience relative supérieure,…), constitue à terme un avantage compétitif pérenne. La deuxième partie aborde la question de la délimitation des « marchés pertinents » lors des opérations de concentration appliquée au marché de l’accès à Internet fixe. La structure de la demande d’accès à Internet est examinée économétriquement afin de vérifier l’existence, ou l’absence, d’une segmentation (voire d’une différenciation) de celle-ci selon que les technologies sont de types haut ou très haut débit. La troisième partie traite de l’effet des ad-blockers sur les médias et fournisseurs de contenus dont le modèle économique repose sur la gratuité. Un modèle de marché biface est spécifié afin de vérifier quel rôle peuvent jouer les fournisseurs d’accès à Internet pour internaliser les externalités de réseau et limiter les phénomènes de congestion. Descripteurs : économie numérique, concurrence, plateformes, concentration, marché pertinent, publicité, externalités de réseau, média / This PhD thesis set the milestones that are relevant for the competitive analysis of markets based on network activities and digital products or services. This work counts three parts, designed as separate essays, and aims to appreciate the impact of the characteristics of these markets on their competitive dynamics. The first part of the thesis tackles the concentration issue of online platforms. We specify a model of two-sided market in order to appreciate the different levels of interdependence on online platforms linking on firms (or advertisers) on one side and audience or consumers on the other side. As a result, network effects (synergies and scale economies relating to the number of users) are such that any competitive advantage (first-mover advantage, better quality or market share…), as low as it can be, turns out to be durable. The second part deals with the “relevant market” delineation in horizontal mergers issue and suggest an application to the retail market for fixed broadband Internet access. We econometrically analyze the demand for broadband access in order to verify whether or not there exists a segmentation (or even a differentiation) of the demand depending on the access technologies that can be very fast broadband or regular broadband access technologies. The third part examines the effects of “ad-blocking” software on the media and content providers whose business model is based on free access. We also specify a model of two-sided market in order to appreciate the role that Internet service providers can play to internalize network effects and to curb congestion phenomena.

- Competitor's Dominant Position and Its Abuse in the Czech and European Law The aim of this thesis is to identify and analyze issues of market dominance and its abuse as one of the most important areas of the competition law. An indispensable part of every analysis of such abuse is also a definition and assessment of the relevant market which we will deal with in a separate section of this thesis. The issue of abuse of a dominant position is analyzed with the help of the competition rules and the judicial practice of the competent authorities, both at the community and national level. First chapters are designed as an introduction to the issue of dominance, offering readers a better understanding of often ambiguous approach to competition law, its restrictions and distortions. We will also be dealing with related terms such as the competitor, the company and their mutual interchangeability. Special attention will be paid to the introduction and further analysis of the relevant market, where the correct definition is the basis for the assessment of any competition case. The issue of relevant market is demonstrated on particular examples, especially on the current case of Student Agency, where the mode of defining the relevant market also decides the final outcome of the case with respect to the...