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We review studies of the impact of credit constraints on the accumulation of human capital. Evidence suggests that credit constraints have recently become important for schooling and other aspects of households' behavior. We highlight the importance of early childhood investments, since their response largely determines the impact of credit constraints on the overall lifetime acquisition of human capital. We also review the intergenerational literature and examine the macroeconomic impacts of credit constraints on social mobility and the income distribution. A common limitation across all areas of the human capital literature is the imposition of ad hoc constraints on credit. We propose a more careful treatment of the structure of government student loan programs and the incentive problems underlying private credit. We show that endogenizing constraints on credit for human capital helps explain observed borrowing, schooling, and default patterns and offers new insights about the design of government policy.

Floor constraints are a prominent feature of many matching markets, such as medical residency, teacher assignment, and military cadet matching. We develop a theory of matching markets under floor constraints. We introduce a stability notion, which we call floor respecting stability, for markets in which (hard) floor constraints must be respected. A matching is floor respecting stable if there is no coalition of doctors and hospitals that can propose an alternative matching that is feasible and an improvement for its members. Our stability notion imposes the additional condition that a coalition cannot reassign a doctor outside the coalition to another hospital (although she can be fired). This condition is necessary to guarantee the existence of stable matchings. We provide a mechanism that is strategy-proof for doctors and implements a floor respecting stable matching.

Ranking algorithms are deployed widely to order a set of items in applications such as search engines, news feeds, and recommendation systems. Recent studies, however, have shown that, left unchecked, the output of ranking algorithms can result in decreased diversity in the type of content presented, promote stereotypes, and polarize opinions. In order to address such issues, we study the following variant of the traditional ranking problem when, in addition, there are fairness or diversity constraints. Given a collection of items along with 1) the value of placing an item in a particular position in the ranking, 2) the collection of sensitive attributes (such as gender, race, political opinion) of each item and 3) a collection of fairness constraints that, for each k, bound the number of items with each attribute that are allowed to appear in the top k positions of the ranking, the goal is to output a ranking that maximizes the value with respect to the original rank quality metric while respecting the constraints. This problem encapsulates various well-studied problems related to bipartite and hypergraph matching as special cases and turns out to be hard to approximate even with simple constraints. Our main technical contributions are fast exact and approximation algorithms along with complementary hardness results that, together, come close to settling the approximability of this constrained ranking maximization problem. Unlike prior work on the approximability of constrained matching problems, our algorithm runs in linear time, even when the number of constraints is (polynomially) large, its approximation ratio does not depend on the number of constraints, and it produces solutions with small constraint violations. Our results rely on insights about the constrained matching problem when the objective function satisfies certain properties that appear in common ranking metrics such as discounted cumulative gain (DCG), Spearman's rho or Bradley-Terry, along with the nested structure of fairness constraints.

This paper discusses the constraints that small jurisdictions face in matters associated with competition law and policy in view of their small domestic market. Special reference will be made to Malta, where competition legislation is modelled on EC law. The thrust of the argument is that certain aspects of competition law may not be desirable to implement or may be more difficult to put in operation in a small state. It is concluded that exceptions, based on considerations such as improved efficiency, distribution, and overall consumer benefit, are likely to be of major relevance to small jurisdictions. ; N/A

Institutions, as mechanisms of social order, often constrain the behavior of individuals within a society. Political institutions constrain the behavior of politicians, financial institutions constrain the behavior of businesses and payment processors and social institutions often constrain the behavior of individuals. These institutions often play an important role in constraining activities that may be seen as illicit or unwanted and careful analysis of these constraints can allow researchers to learn more about activities that are often hidden or go unreported.This dissertation explores the role of institutional constraints on unwanted behavior by studying deforestation in Brazil and Malawi as well as underground activity in fraudulent software sales. These cases share the commonality that they are influenced by institutional constraints. Politicians in Brazil are constrained by reelection incentives, perpetrators of fraudulent antivirus software are constrained by payment processors and the cultural practice of ethnic favoritism in public good provision leads to particular ethnic groups in Malawi receiving much more fertilizer subsidies than others.The first chapter examines deforestation in Brazil. Local political authority (formal or informal) over natural resources may create rents for politicians. The political decision to use or allocate resources involves balancing private rents with reelection prospects. I examine the case of deforestation in Brazil and a presidential decree granting the federal government the authority to punish counties that failed to limit total deforestation within their borders. This collective punishment aimed to generate pressure on local politicians to slow deforestation. Using binding term limits as a source of variation in reelection eligibility, I find eligibility has no effect on deforestation prior to the decree. After the decree, reelection eligible mayors reduced annual deforestation 10% more than mayors ineligible for reelection. These findings are consistent with the equilibrium outcome of a lobbying model. Policies such as sanctions, which target the electorate in order to influence political behavior, may be less effective when politicians are not accountable to voters.The second chapter examines Fake antivirus (AV) programs which have been utilized to defraud millions of computer users into paying as much as one hundred dollars for a phony software license. As a result, fake AV software has evolved into one of the most lucrative criminal operations on the Internet. In this chapter, we examine the operations of three large scale fake AV businesses, lasting from three months to more than two years. More precisely, we present the results of our analysis on a trove of data obtained from several backend servers that the cybercriminals used to drive their scam operations. Our investigations reveal that these three fake AV businesses had earned a combined revenue of more than $130 million dollars. A particular focus of our analysis is on the financial and economic aspects of the scam, which involves legitimate credit card networks as well as more dubious payment processors. In particular, we present an economic model that demonstrates that fake AV companies are actively monitoring the refunds (chargebacks) that customers demand from their credit card providers. When the number of chargebacks increases in a short interval, the fake AV companies react to customer complaints by granting more refunds. This lowers the rate of chargebacks and ensures that a fake AV company can stay in business for a longer period of time. However, this behavior also leads to unusual patterns in chargebacks, which can potentially be leveraged by vigilant payment processors and credit card companies to identify and ban fraudulent firms. This chapter is joint work with Brett Stone-Gross, Richard Kremmerer, Christopher Kruegel, Douglas Steigerwald, and Giovanni Vigna and was published as Stone-Gross et al. (2013).The final chapter returns to deforestation and studies it in the context of agriculture in Malawi. The effect of development policies on the environment is often ambiguous ex ante. Programs designed to improve agricultural productivity may increase deforestation by raising the marginal productivity of agricultural land, thus increasing the demand for land clearing. However, in a setting of subsistence farming on unproductive land, increasing agricultural productivity may reduce the need to shift cultivation to maintain the desired yields. This chapter examines the impact of agricultural subsidies on deforestation in Malawi by leveraging ethnic favoritism in government resource allocation. By exploiting a change in the ethnicity of the Malawi president following the 2004 election, we show that coethnic districts received more fertilizer subsidies and experienced significant declines in deforestation compared to districts with other predominant ethnicities. This paper studies a case in which poverty alleviation programs have beneficial environ- mental impacts demonstrating that, in certain contexts, input subsidies may provide a 'win-win' scenario. This chapter is joint work with Conor Carney.

تعاني المشاريع الانشائية في العراق من القيود (الاقتصادية والتقنية والسياسية والقانونية والبيئية) التي تعوق عملها لذا من الضروري تحديد هذه القيود من خلال إتباع النظريات من أجل تحديدها بدقة وتوفير معلومات مفيدة لاتخاذ قرارات حول قيود الإنتاج وتأثيرها على العمل، يعرف القيد بأنه: أي محدد يمنع المشروع من تحقيق أهدافه أو تحقيق مستوى من الأداء بالنسبة لهذا الهدف، لذا لا بد من استخدام بعض النظريات، بما في ذلك نظريات القيود التي تحدد لها وإيجاد حلول لتلك العقبات من خلال مخططات منهج التفكير. وتعرف نظرية القيود: بأنها "فلسفة إدارية شاملة تهدف إلى تحقيق مستمر لأكثر من هدف واحد في المشروع. فإذا كان المشروع يعمل على تحقيق إنجاز معين في مشروع ما ،بعد تحديد القيود وأنواعها وكل حسب مدى اهميته وتأثيره سوف يتم ايجاد الحلول لها بواسطة "منهج ألتفكير" الذي يعرف بأنه : يوفر اطار متكامل لإلية عمل المشاريع اذ يساعد على تحديد ومعالجة المعوقات التي تعاني منها المشاريع والعمل على تحديد الحلول الملائمة وذلك من خلال مجموعة من مخططات التفكير المنطقية التي تبدأ بدراسة واقع الحالي للمشروع الذي يعاني من المعوقات ومن ثم البحث عن مجموعة المعوقات التي تعانيها ويتم ترتيب المعوقات بحسب اهميتها ومدى ارتباطها ببعض وذلك من أجل تحديد المشاكل الجوهرية التي تسبب في حدوث الواقع غير المرغوب، يتم بعد ذلك تقديم مجموعة من الحلول المقترحة ويتم دراسة هذه الحلول وبيان النتائج المستقبلية لكل حل وفائدته في معالجة المشكلة المحددة ومدى الأثر المستقبلي لتطبيقه، اذ ستتمثل المنهجية المستخدمة في البحث في استخراج المؤشرات من الإطار النظري والعملي وإيجاد الحلول من خلال مخطط منهج التفكير للخروج بعدد من الاستنتاجات والتوصيات الرامية إلى تحقيق أهداف البحث. ; Construction projects in Iraq are suffering from constraints (financial, technical, political, legal and environmental) that hamper their work. It is therefore necessary to identify these constraints by following the theories in order to accurately identify and provide useful information to make decisions about production constraints and their impact on work. To achieve its objectives or achieve a level of performance for this goal, so it is necessary to use some theories, including theories of constraints that identify ...

Deontic constraints prohibit an agent performing acts of a certain type even when doing so will prevent more instances of that act being performed by others. In this article I show how deontic constraints can be interpreted as either maximizing or non-maximizing rules. I then argue that they should be interpreted as maximizing rules because interpreting them as non-maximizing rules results in a problem with moral advice. Given this conclusion, a strong case can be made that consequentialism provides the best account of deontic constraints.

Abstract In my research I analysed the feasibility requirements of normative political theories. Here my attempt is to answer to the question: which facts affect the feasibility of normative political prescriptions? I structured the thesis in five chapters. In the first chapter, I will provide a normative argument in order to hold that normative political prescriptions should respect a feasibility requirement. I will maintain that normative political prescriptions can imply legal rules, and legal rules are coercible. I will assume that it would be morally unacceptable to sanction people who do not act in accordance with a (set of) prescription(s) if it was impossible for those people to act in accordance with that (set of) prescription(s). Consequently, I will conclude that normative political prescriptions should adhere to a certain specification of the maxim 'ought implies can' ('OIC'). In particular, this means that normative political prescriptions does exist in a hypothetical set of 'all normative political prescriptions' only if people can satisfy it. I will argue that the term 'can' could assume two meanings: 'can as being possible' and 'can as being able to'. I will conclude this chapter by claiming that: prescriptions are feasible or not whether or not it is possible for human beings to act in accordance with a prescribed (of forbidden) course of action; prescriptions are more or less feasible depending on how much that human beings are able to act in accordance with a prescribed (or forbidden) course of action. In the second chapter, I will mainly review the state of art concerning the analysis of feasibility and I will criticize it in some regards. Here, I will introduce terms and commons standpoints found in the literature about the feasibility of normative theories. Then, I will pay attention to the list of facts that are usually considered to be feasibility constraints. Feasibility constraints will be distinguished between hard feasibility constraints (logic rules, physical and biological laws) and soft feasibility constraints (mainly: state of technology, institutions, economy, culture, human beings' features). I will show that the selection of soft constraints is a relevant problem for the analysis of feasibility. Hence, we should distinguish between simple facts and facts that are soft feasibility constraints. In order to draw this distinction, I will suggest that it is necessary to find out an adequate formal criterion for the selection of soft feasibility constraints. In the following two chapters, I will propose two different kinds of criteria for the selection of soft constraints, namely normative and practical criteria. These criteria propose different ways to distinguish facts affecting the feasibility of prescriptions from simple facts. In the third chapter, I will propose two normative criteria different kinds of criteria for the selection of soft constraints. The hypothesis behind normative criteria is that: 'all and only normatively (or morally) valuable facts should be considered soft constraints'. I will criticize normative criteria for the selection of soft constraints for two reasons. First, these criteria are sensitive to controversial implications that do not fit with my definition of feasibility and with the common sense definition of 'feasible as capable of being successfully used'. Second, I will argue that they lead to viciously circular arguments for the selection of soft feasibility constraints and that, for this reason, we should not accept them. Therefore, I will conclude that normative criteria are not adequate to select soft feasibility constraints In the fourth chapter, I will consider a practical criterion for the selection of soft constraints. This criterion selects soft constraints paying attention to the influence that certain facts have on the success of certain prescriptions. Although it needs some refinements, I will show that this criterion is consistent with the commonly accepted definition of feasibility and with my own definition of feasibility. Therefore, I will consider it adequate to select feasibility constraints. Thanks to this criterion, I will criticize one of the main tenets of the literature about feasibility. That is to say, I will conclude that institutional facts, cultural facts and economic facts should not be considered feasibility constraints since they are not independent from what people want. Hence, I will show that these social facts, which are usually and incontestably considered soft constraints, do not matter for the feasibility of normative political prescriptions. In the last chapter I will propose an answer to the research question. I will hold that facts constraining the feasibility of normative political prescriptions are: first (hard constraints), logic rules, physical laws, biological laws and any other fact undermining the feasibility of a prescription in any place of the world at any time; second (soft constraints), others' motivations, lacking material resources and human needs.

Part Part One: Personality -- chapter I The Humanization of Infants -- chapter II The Oedipus Complex -- chapter III Who is Normal? -- chapter IV Sex, Repression, and Beyond -- chapter V Treatment -- chapter VI The Family as an Industry -- part Part Two: Society -- chapter VII Groups -- chapter VIII The Basic Tension of Group Membership -- chapter IX Rivalry, Competition, and Conflict -- chapter X Leadership, Authority, and Power -- chapter XI Culture, Passion, and Affectations -- chapter XII The Conflict between Economic Progress and Social Well-Being -- chapter XIII Class, Estate, and Caste -- chapter XIV Expansion, Mobility, and the Class System -- chapter XV Democracy and Elites -- chapter XVI Roles and the Prestige of Histrionies -- chapter XVII Snobbery (and the Supreme Court's Prescription) -- part Part Three: Popular Culture -- chapter XVIII Why Is the Crowd Lonely? -- chapter XIX Of Happiness and of Despair We Have No Measure -- part Part Four: The Proper Study of Mankind -- chapter XX Man as an Object of Science.