The aim of the diploma thesis is a comprehensive analysis of the concept of collective dominance, in particular with reference to the evaluation of its applicability and utility in practice. The first chapter deals with the main features of the oligopoly market and Czech and European legal provisions on the abuse of a dominant position and mergers within which it has evolved. On base of the analysis of Court of Justice and General Court judgements the second chapter explains the notion of the collective dominance and examines the obligatory conditions of the collective dominance, as well as the factors which influence these conditions. The third chapter concerns the concept of collective dominance with regard to competition law taxonomy. It compares not only the test of collective dominance applied pursuant to the article 102 TFEU with the test applied according to the Council Regulation (EC) No 139/2004 on the control of concentrations between undertakings, but also the concept of collective dominance with the agreements pursuant to the article 101 TFEU. It also deals with abusive practices typical for oligopolies. Beside the explanation of the UK legislation the last two chapters illustrate decisions of competition authorities in the Czech Republic and in the United Kingdom and analyse and compare them. The diploma thesis is concluded by the analysis of main shortcomings of the concept of collective dominance and the evaluation of actual state of the examined topic with the aim to abstractly summarize knowledge gained through the thesis.

It's a subject of extensive discussion whether or not fuel prices on gas stations respond faster on an increase of oil price than on its decrease. Though this phenomenon is widely discussed in scientific literature, there's still no study focused on an asymmetric behavior of fuel prices on the Czech market. This diploma thesis fills the gap and explores the reaction of fuel prices in response to cost shocks in the environment of the Czech Republic. At the first section of thesis, there is described several economic theories explaining asymmetric reaction - especially the theories based on consumer behavior under the imperfect information assumption and the theory of tacit collusion according to which the price of previous period provides companies on oligopolistic market with a focal price for implicit cartel agreement. In the Empirical part of the thesis, I use an error correction model allowing asymmetric reaction to analyze if the retail fuel prices in the Czech Republic really react with different lag on positive and negative cost shocks. Based on several time series of gasoline and diesel prices, presence of asymmetric price reaction was proven between wholesale and retail level of supply chain.

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<p dir="ltr">Distributed cryptographic protocols typically assume a bounded number of malicious parties (who behave arbitrarily) in the system---and in turn, a lower bound on the number of <i>honest</i> parties (who follow and only follow a protocol faithfully/honestly without performing unspecified computations)---for their respective security guarantees to hold. However, when deploying these protocols in practice, the nature of computing parties does not necessarily align nicely with the protocols' assumptions. Specifically, there may be only a few honest/compliant parties, or none exists. Instead, non-malicious parties may be <i>semi-honest</i> (who follow the protocol specifications but are curious to learn as much information as possible from semi-honest parties' transcripts) or <i>rational</i> (who take actions that maximize their utilities instead of actions benefiting the protocol the most, e.g., performing extra computations or not following protocols). In such cases, the security guarantees of such protocols may deviate greatly in real life from what is theoretically promised, leaving a huge gap between theory and practice. </p><p dir="ltr">In this thesis, I bridge such a gap by enhancing the fault tolerance of various distributed cryptographic primitives by <i>relaxing the assumption on the existence of honest parties</i>.</p><p dir="ltr">First, in the context of <b>secure multi-party computations</b>, without honest parties, my goal is to induce honest (i.e., not compromising correctness) and non-curious (i.e., not harming privacy) behaviors from rational participants via game theoretic and cryptographic techniques. In particular, I first demonstrate how to ensure protocol correctness and deter collusion among parties to recover secrets---which also breaks privacy---in multiserver private information retrieval with a singleton access structure. Then for primitives with more general (non-singleton) access structures, I introduce a distinct treatment through the lens of verifiable secret sharing. The two solutions are designed with a public bulletin board, commitment schemes, digital signature schemes, zkSNARKs (zero-knowledge succinct non-interactive arguments of knowledge), and distinct incentive structures tailored for varying access structures underlying the schemes.</p><p dir="ltr">Second, in <b>permissionless blockchain systems</b>, for protocols without privacy guarantees like computation outsourcing and consensus, my goal is to incentivize rational parties to behave correctly. This means to act according to the protocol specifications or as implied by the security requirements of the primitive, e.g., fairly distribute rewards to participants based on contributions in proof-of-work (PoW) blockchains. Specifically, I present a defense against an undercutting attack in PoW blockchains from a game theory perspective and propose a decentralized computation outsourcing protocol built on permissionless blockchain systems based on multi-unit auctions.</p>

La thèse a été évaluée par les personnes suivantes: Carlo Morselli, directeur de recherche et professeur à l'École de criminologie; Anthony Amicelle, président du jury et professeur à l'École de criminologie; Jean Bérard, membre du jury et professeur à l'École de criminologie; Carla Nagels, évaluatrice externe et professeur à l'Université libre de Bruxelles L'auteur aimerait remercier le Fonds de recherche du Québec - Société et culture (FRQSC), le Centre international de criminologie comparée (CICC) et l'École de criminologie pour le support financier octroyé à différentes étapes de la rédaction de la thèse. / La recherche trouve ses origines d’un scandale touchant l’industrie de la construction et les milieux politiques au Québec de la fin des années 2000 (à travers les allégations de corruption et de collusion soulevées par les médias) à la fin novembre 2015 (avec le dépôt du rapport final de la Commission d’enquête sur l’octroi et la gestion des contrats publics dans l’industrie de la construction, ci-après CEIC). L’argument principal est que les années de scandale ont permis au Québec de transiter d’une province considérée comme la terre mythique de la corruption au Canada à une entité développant une des structures anticorruptions les plus novatrices et sophistiquées dans le monde. La thèse est construite comme une étude de cas qui s’intègre aux trois grandes sphères de l’étude du phénomène criminel telles que définies par Sutherland et Cressey, à savoir le passage à l’acte, la réaction sociale et le contrôle social (1947, p.1). Dans l’étude du passage à l’acte, le concept de crime étatico-corporatif est mis à profit afin d’exposer l’aspect symbiotique des systèmes criminels alimentés à travers une interaction fondamentale entre poursuite d’intérêts publics et poursuite d’intérêts privés. De tels systèmes furent en effet identifiés dans plusieurs municipalités du Québec. Pour cette partie de la thèse, les données relatives à l’ensemble des contrats de construction octroyés par appel d’offres public par la ville de Laval dans son histoire (1965-2013) sont analysées à travers diverses mesures de réseaux sociaux. Cette portion de la thèse utilise également les témoignages issus des travaux de la CEIC, et des entretiens semi-directifs réalisés avec des acteurs provenant de diverses autorités de lutte à la collusion (truquage des appels d’offres) et à la corruption au Québec. La combinaison de ces méthodes permet d’évaluer la nature intégrée, historique et spatiale des délinquances recensées au sein de diverses municipalités, avec des indicateurs de collusion qui remontent aussi loin qu’à la création de la municipalité lavalloise dans les années 1960. Dans l’étude de la réaction sociale, un modèle d’analyse intégratif emprunté au domaine de la sociologie de l’action publique (Lascoumes et LeGalès, 2012) est utilisé pour mettre en relief les forces structurelles, organisationnelles et individuelles derrière la constitution du scandale québécois. Cette deuxième grande section de la thèse illustre comment ce scandale s’insère dans des tendances nationales et internationales d’intolérance accrue du public et d’intensification des contrôles à l’égard des actes criminels (corruption, collusion, pots-de-vin, fraude) révélés au coeur du scandale. Enfin, dans l’étude du contrôle social, l’analyse des témoignages issus des audiences de la CEIC est jumelée aux données découlant d’entretiens semi-directifs réalisés avec 22 acteurs provenant d’agences de contrôle créées à la suite du scandale : l’Unité permanente anticorruption (UPAC), le Bureau de l’inspecteur général (BIG) de la ville de Montréal, et le Bureau d’intégrité et d’éthique de Laval (BIEL). Cette dernière section illustre comment la transition d’une scène réglementaire permissive et hautement déficiente à un environnement réglementaire axée sur une mobilisation sans précédent de ressources policières, sur le partage d’information et sur la poursuite des conduites illégales au pénal s’avère très avantageuse, mais s’est accomplie – et s’accomplit toujours – à travers de nombreux défis pour les contrôleurs. / The research originated from a political scandal which spanned several years (2009-2015) in the province of Quebec. The thesis’ main argument is that the scandal years saw Quebec transformed from being considered the “historical golden land” of Canadian corruption into a province which developed one of the country’s most sophisticated systems of corruption and white-collar crime control. The thesis was constructed as a case-study, and addressed the three principal objects of criminological analysis: the breaking of laws, the making of laws, and the reaction to the breaking of laws (Sutherland and Cressey, 1947, p.1). The study applied multiple methods to achieve these goals. In the study of criminal decision-making (breaking of laws), Kramer and Michalowski’s (2006) state-corporate crime concept was applied to demonstrate the presence of multifactorial features of criminal systems fuelled by misbehaving at the intersection of private and public interests. Such conspiracies were found to be generalized across several municipalities throughout the province. For this portion of the thesis, data on all construction contracts awarded through public procurement in the entire history of what appeared to be one of Canada’s most corrupt municipalities, Laval (the 13th largest in the country), was systematically collected from 1965 to 2013. It was then analyzed using various social network measures. Testimonies from Quebec’s Commission of inquiry on the awarding and management of public contracts in the construction industry (hereafter, CEIC) were also coupled with a dozen of interviews conducted with regulators and corruption authorities in Quebec. The combination of methods helped assess the integrated, spatial and historical nature of illicit activities which undergirded many municipalities, Laval being one of the most notorious one. Traces of bid-rigging indicators in public procurement were indeed traced back to as early as the city’s founding in the 1960s. In the study of the making of laws, Lascoumes and Le Galès’ (2002) sociology of public action framework was expanded to investigate the structural, organizational, and individual forces behind the Quebec scandal. This section of the thesis unravels the sudden urge to legislate and investigate schemes that were deeply rooted in the province’s history. By making sense of the Quebec scandal, this sub-section demonstrates how larger structural and contextual factors gradually established increased incentives for elected officials to enhance legal and institutional controls on white-collar and corporate crimes which were found to be systemic across Quebec’s construction and political scenes. Finally, in the study of the reaction to the breaking of laws, testimonies from the CEIC were combined with interviews conducted with 22 actors in control agencies established as a direct result of the scandal: the Permanent Anticorruption Unit (UPAC in French), the Inspector General Bureau (BIG in French) of the city of Montreal, and the Bureau of integrity and ethics of Laval (BIEL in French). This last section shows how transitioning from a state of practical passivity to one of intense controls, monitoring, institutional rearrangements, and legislative efforts was accompanied, for regulatory and police authorities, by several benefits but substantial challenges as well.

This research looks at identifying and classifying changes in evolving software by making simple textual comparisons between groups of source code files. The two areas investigated are software origin analysis and collusion detection. Textual comparison is attractive because it can be used in the same way for many different programming languages. The research includes the first major study using machine learning techniques in the domain of software origin analysis, which looks at the movement of code in an evolving system. The training set for this study, which focuses on restructured files, is created by analysing 89 software systems. Novel features, which capture abstract patterns in the comparisons between source code files, are used to build models which classify restructured files fromunseen systems with a mean accuracy of over 90%. The unseen code is not only in C, the language of the training set, but also in Java and Python, which helps to demonstrate the language independence of the approach. As well as generating features for the machine learning system, textual comparisons between groups of files are used in other ways throughout the system: in filtering to find potentially restructured files, in ranking the possible destinations of the code moved from the restructured files, and as the basis for a new file comparison tool. This tool helps in the demanding task of manually labelling the training data, is valuable to the end user of the system, and is applicable to other file comparison tasks. These same techniques are used to create a new text-based visualisation for use in collusion detection, and to generate a measure which focuses on the unusual similarity between submissions. This measure helps to overcome problems in detecting collusion in data where files are of uneven size, where there is high incidental similarity or where more than one programming language is used. The visualisation highlights interesting similarities between files, making the task of inspecting the texts easier for the user.

Diese Dissertation besteht aus drei unabhängigen Kapiteln in Vertragstheorie und Industrieökonomik. Die Kapitel 1 und 2 bearbeiten Fragestellungen der Vertragstheorie. In diesen Kapiteln studiere ich die Ausprägung der Informationsasymmetrien, die in vertraglichen Beziehungen entstehen, wenn die schlechter informierte Partei versucht ihren Informationsnachteil gegenüber dem Vertragspartner zu reduzieren. In Kapitel 1 analysiere ich die Möglichkeit, dass die schlechter informierte Vertragspartei eine dritte Partei – einen Berater oder Supervisor – konsultiert, der jedoch mit der besser informierten Partei kolludieren könnte. In Kapitel 2 analysiere ich den Fall, in dem die schlechter informierte Vertragspartei selbst Monitoring-Aktivitäten aufnehmen kann, um zusätzliche Information zu sammeln. In Kapitel 3 untersuche ich den Effekt von Informationsasymmetrien innerhalb von Unternehmen auf diskriminierende Preissetzungsstrategien in Zwischengutmärkten. Hierbei analysiere ich Preisdiskriminierung und die aus dieser resultierenden Wohlfahrtseffekte in einem Modell eines Zwischengutmarktes, auf dem ein monopolistischer Verkäufer ein Zwischengut an zwei Abnehmer verkauft, die aufgrund ihrer unterschiedlichen vertikalen Organisation unterschiedlich stark von Agenturkosten betroffen sind. / This dissertation consists of three independent chapters in the fields of contract theory and industrial organization. Chapters 1 and 2 are concerned with topics in contract theory. In these chapters, I study the form of information asymmetry that arises in contractual relationships where the less knowledgeable party can reduce its informational disadvantage vis-à-vis the contractual partner. In Chapter 1, I analyze the opportunity of the less knowledgeable party to consult a third party – an expert or supervisor – who can provide advice. In Chapter 2, the less knowledgeable party can itself engage in monitoring activities to gather additional information. In Chapter 3, I explore the effect of information asymmetry within firms on discriminatory pricing in intermediate good markets. In particular, I study price discrimination and the associated welfare effects in an intermediate good market where a monopolistic upstream firms sells an input to downstream firms that vary in their exposure to the problem of asymmetric information due to different degrees of vertical integration.

Online examinations are an integral component of many online learning environments and a high-stake process for students, teachers and educational institutions. They are the target of many security threats, including intrusion by hackers and collusion. Collu-sion happens when a student invites a third party to impersonate him/her in an online test, or to abet with the exam questions. This research proposed a profile-based chal-lenge question approach to create and consolidate a student's profile during the learning process, to be used for authentication in the examination process. The pro-posed method was investigated in six research studies using a usability test method and a risk-based security assessment method, in order to investigate usability attributes and security threats. The findings of the studies revealed that text-based questions are prone to usability issues such as ambiguity, syntactic variation, and spelling mistakes. The results of a usability analysis suggested that image-based questions are more usable than text-based questions (p < 0.01). The findings identified that dynamic profile questions are more efficient and effective than text-based and image-based questions (p < 0.01). Since text-based questions are associated with an individual's personal information, they are prone to being shared with impersonators. An increase in the numbers of chal-lenge questions being shared showed a significant linear trend (p < 0.01) and increased the success of an impersonation attack. An increase in the database size decreased the success of an impersonation attack with a significant linear trend (p < 0.01). The security analysis of dynamic profile questions revealed that an impersonation attack was not successful when a student shared credentials using email asynchronously. However, a similar attack was successful when a student and impersonator shared information in real time using mobile phones. The response time in this attack was significantly different when a genuine student responded to his challenge questions (p < 0.01). The security analysis revealed that the use of dynamic profile questions in a proctored exam can influence impersonation and abetting. This view was supported by online programme tutors in a focus group study.

Cette thèse contient trois études sur le fonctionnement des banques.<p>Le premier Chapitre analyse empiriquement comment la capacité d’offrir des emprunts à long terme est influencée par la dimension des intermédiaires financiers.<p>Le deuxième Chapitre analyse, avec un model théorique caractérisé par la présence de soft-budget constraint, ratchet effect et short-termism, comment la pression compétitive influence la capacité des banque de financer le firmes ayant des projets de bonne qualité.<p>Le troisième Chapitre examine, avec un model théorique du type moral hazard common agency, le conflits d'intérêts des banques universelles.<p><p>Financial intermediaries are recognized to promote the efficiency of resource allocation by mitigating problems of incentives, asymmetric information and contract incompleteness. The role played by financial intermediaries is considered so crucial that these institutions have received all over the world the greatest attention of regulators.<p>Across and within banking sectors it is possible to observe a wide variety of intermediaries. Banks may differ in their size, market power and degree of specialization. This variety raises interesting questions about the features of a well functioning banking sector. These questions have inspired an important body of economic literature which, however, is still inconclusive in many aspects. This dissertation includes three studies intending to contribute in this direction.<p>Chapter 1 will empirically study the willingness of smaller and larger lenders to grant long-term loans which, as credit to SME's, constitute an opaque segment of the credit market. Chapter 2 analyzes, with a theoretical model, the effects of competition on the efficiency of the banking sector when this is characterized by dynamic commitment issues which brings to excessive refinancing of bad quality investments (so called soft-budget constraint) or excessive termination of good ones (ratchet effect and short-termism). Chapter 3 presents a model to investigate to what extent the distortions posed by conflicts of interest in universal banks can be addressed through the provision of appropriate incentive schemes by the different categories of clients. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

This Diploma Thesis is focused on the issue of the value of a child's wish in the framework of the divorce/break-up settlement. In the theoretical part of this thesis, the child's status, its right to participate and the means of ensuring that in the mentioned framework are presented. In this thesis, the term child's wish is also discussed in the context of defending child's own interest. In the last chapter of the theoretical part, there is illustrated the suitable way how to interview a child. The aim of the practical part is to, through half-structured interviews with the professionals taking part in this process and an analysis of those interviews, answer the main research question: How do the professionals taking part in the divorce/break-up settlement perceive and deal with the child's wish in this process? The research part of this thesis is also focused on the possible space for change in the contemporary attitude towards children as participants of trials.