Pareto optimal matchings in many-to-many markets with ties

We consider Pareto optimal matchings (POMs) in a many-to-many market of applicants and courses where applicants have preferences, which may include ties, over individual courses and lexicographic preferences over sets of courses. Since this is the most general setting examined so far in the literature, our work unifies and generalizes several known results. Specifically, we characterize POMs and introduce the Generalized Serial Dictatorship Mechanism with Ties (GSDT) that effectively handles ties via properties of network flows. We show that GSDT can generate all POMs using different priority orderings over the applicants, but it satisfies truthfulness only for certain such orderings. This shortcoming is not specific to our mechanism; we show that any mechanism generating all POMs in our setting is prone to strategic manipulation. This is in contrast to the one-to-one case (with or without ties), for which truthful mechanisms generating all POMs do exist

Three Essays in Competition Policy.

This thesis focuses on different aspects of Competition Policy and analyses questions related to market power, collusion and the European Commission's fining policy. The first chapter provides a theoretical setting to study a particular abuse of dominant position, known as margin (or price) squeeze. It explores the conditions under which margin squeeze arises as an equilibriumoutcome and discusses policy implications of introducing price squeeze testing. In the field of cartel detection, the leniency program has been instrumental in competition authorities' fight against cartels. This is the topic of the second paper, which examines the deterrence effect of the leniency program in a setup where all cartels are failing cartels. The third chapter provides an overview of the fining decisions of the European Commission in the field of antitrust. It analyses the incentives of firms to appeal Commission infringement decisions and examines whether the fining Guidelines have led to lower appeal rates, possibly through providing greater transparency in the way fines are set.

Pareto optimality in many-to-many matching problems

Consider a many-to-many matching market that involves two finite disjoint sets, a set A of applicants and a set C of courses. Each applicant has preferences on the different sets of courses she can attend, while each course has a quota of applicants that it can admit. In this paper, we examine Pareto optimal matchings (briefly POM) in the context of such markets, that can also incorporate additional constraints, e.g., each course bearing some cost and each applicant having a limited budget available. We provide necessary and sufficient conditions for a many-to-many matching to be Pareto optimal and show that checking whether a given matching is Pareto optimal can be accomplished in 0(1 A 12 I C 12) time. Moreover, we provide a generalized version of serial dictatorship, which can be used to obtain any many-to-many POM. We also study some structural questions related to POM. We show that, unlike in the one-to-one case, finding a maximum cardinality POM is NP-hard for many-to-many markets. (C) 2014 Elsevier B.V. All rights reserved

Three Essays in Competition Policy

Defense Date: 5 May 2011Jury Members: Prof. Massimo Motta, Supervisor, Universitat Pompeu Fabra Prof. Michele Polo, Università Bocconi Prof. Fernando Vega Redondo, EUI Prof. Nikolaos Vettas, Athens University of Economics and BusinessThis thesis focuses on different aspects of Competition Policy and analyses questions related to market power, collusion and the European Commission's fining policy. The first chapter provides a theoretical setting to study a particular abuse of dominant position, known as margin (or price) squeeze. It explores the conditions under which margin squeeze arises as an equilibriumoutcome and discusses policy implications of introducing price squeeze testing. In the field of cartel detection, the leniency program has been instrumental in competition authorities' fight against cartels. This is the topic of the second paper, which examines the deterrence effect of the leniency program in a setup where all cartels are failing cartels. The third chapter provides an overview of the fining decisions of the European Commission in the field of antitrust. It analyses the incentives of firms to appeal Commission infringement decisions and examines whether the fining Guidelines have led to lower appeal rates, possibly through providing greater transparency in the way fines are set