Dipolar Bose gases: Many-body versus mean-field description

We characterize zero-temperature dipolar Bose gases under external spherical confinement as a function of the dipole strength using the essentially exact many-body diffusion Monte Carlo (DMC) technique. We show that the DMC energies are reproduced accurately within a mean-field framework if the variation of the s-wave scattering length with the dipole strength is accounted for properly. Our calculations suggest stability diagrams and collapse mechanisms of dipolar Bose gases that differ significantly from those previously proposed in the literature

OFFICE AUTOMATION: A MANAGEMENT BY CONSTRAINTS APPROACH

Information Systems Working Papers Serie

Consolidation of Customer Orders Into Truckloads at a Large Manufacturer

Journal of the Operational Research Society, 48, pp. 779-785.We describe the development and operation of an interactive system based on a mathematical optimization model which is used by a major US manufacturer to consolidate customer orders into truckloads. Dozens of users employ the system daily for planning delivery of orders from manufacturing plants to customers by truckload carriers, saving numerous hours of the users' time and reducing transportation costs

Redistributing Optimally: Of Tax Rules, Legal Rules, and Insurance

From the beginning of the law and economics movement, normative legal economists have focused almost exclusively on evaluating the efficiency of alternative legal rules. The distributional consequences of legal rules, therefore, have largely been ignored. It is tempting to conclude that legal economists are hostile or indifferent to concerns of distributional fairness. In fact, however, the discipline of economics has a great deal to say about distributional policy. The normative branch of economics, known as welfare economics, has always been deeply concerned with distributional issues. It is not that welfare economists purport to know a priori the right or optimal distribution of resources. To the contrary, the standard approach among public finance economists has been to remain neutral on the types of inequality in society that ought to be the target of redistributive policy and how much, if any, redistribution is appropriate. If those same economists, however, were provided with a theory of distributive justice, they then could build that theory into their framework for evaluating public policy. Indeed, economists have created mathematical models of tax regimes to accommodate any number of theories of distributive justice: from the Rawlsian maximin criterion, which manifests a special concern for the well-being of the least advantaged members in society, to the various versions of utilitarianism, which, depending on the assumptions, can justify complete equalization of income or redistribution from the worse off to the better off. Again, while economists are able to build these theories into their models, they typically do not endorse any particular theory of distributive justice

Redistributing Optimally: Of Tax Rules, Legal Rules, and Insurance

From the beginning of the law and economics movement, normative legal economists have focused almost exclusively on evaluating the efficiency of alternative legal rules. The distributional consequences of legal rules, therefore, have largely been ignored. It is tempting to conclude that legal economists are hostile or indifferent to concerns of distributional fairness. In fact, however, the discipline of economics has a great deal to say about distributional policy. The normative branch of economics, known as welfare economics, has always been deeply concerned with distributional issues. It is not that welfare economists purport to know a priori the right or optimal distribution of resources. To the contrary, the standard approach among public finance economists has been to remain neutral on the types of inequality in society that ought to be the target of redistributive policy and how much, if any, redistribution is appropriate. If those same economists, however, were provided with a theory of distributive justice, they then could build that theory into their framework for evaluating public policy. Indeed, economists have created mathematical models of tax regimes to accommodate any number of theories of distributive justice: from the Rawlsian maximin criterion, which manifests a special concern for the well-being of the least advantaged members in society, to the various versions of utilitarianism, which, depending on the assumptions, can justify complete equalization of income or redistribution from the worse off to the better off. Again, while economists are able to build these theories into their models, they typically do not endorse any particular theory of distributive justice

A Group’s a Group, No Matter How Small: An Economic Analysis of Defamation

Consider the following: A Jews-for-Jesus bulletin reports, falsely, that a Jewish woman became “a believer in the tenets, the actions, and the philosophy of Jews for Jesus.” Does this publication constitute defamation? Should defamatoriness be determined in accordance with the views of the general non- Jewish community, with those of the Jewish minority, or with a normative ethical commitment? Our Article aims to provide the answers. Part I demonstrates that the de finition of defamatoriness in common law jurisdictions is essentially empirical and distinguishes between the two leading tests—the English test and the American test. Part II.A describes the English, or general community test, whereby a statemen t is defamatory if considered so by the “right thinking members of the public at large.” Part II.B details the American, or sectorial test, whereby a statement is defamatory if considered so by a substantial and respectable minority. A third possible empirical test, whereby the defamatory potential of a statement may be tested within a small group, has not been adopted in any jurisdiction. Part III, however, demonstrates that the small group test is an economically preferable option to both the English and American tests. Part III conducts two separate economic analyses of the alternative empirical tests for defamation. First, we study the relationship between the view of the community and the views of the individuals who comprise the community. We show that the defamation cases should be decided according to the unanimity rule: A statement may be conside red defamatory only when all individuals in the relevant community consider it so. Because this rule is implausible except in the case of the small group test, it suggests that both the English and American tests lack a solid theoretical foundation. Second, we study the costs and benefits associated with the various tests and find that the American sectorial test is no longer optimal. As a result, we argue that it is preferable to adopt the small group test when deciding cases of defamation

Revisiting the Roles of Legal Rules and Tax Rules in Income Redistribution: A Response to Kaplow & Shavell

The debate over whether legal rules should be used to redistribute resources in society or whether redistribution should be left exclusively to the tax-and-transfer system has long occupied philosophers, political theorists, economists, and legal academicians. For many years, the conventional wisdom on this question among legal scholars seemed to be that blanket generalizations were inappropriate. All systems of redistribution distort individuals\u27 choices and entail administrative costs. Therefore, the argument went, a universal preference for using the tax-and-transfer system to redistribute is not justified. Rather, the choice among institutions to accomplish society\u27s redistributive goals was considered to be an empirical one which must be resolved on a case-by-case basis, in the light of detailed information about the circumstances likely to influence the effectiveness of each method of redistribution. At some point, however, a contrary view developed among economists, a view that has become the new conventional wisdom: that income (or wealth) redistribution is always better accomplished through the tax-andtransfer system than through the legal system. One of the arguments traditionally offered to support this view is that redistribution through the legal system is by nature more haphazard (in the sense of less comprehensive and less precise) than redistribution through the tax system. That is, the tax system can redistribute from all better-off to all worse-off individuals, whereas the legal system can redistribute only from those better off to those worse off who are subject to the legal rule in question. In addition, it was often argued that the legal system\u27s capacity for income redistribution is, in any event, small because redistributive legal rules will be effective only in settings in which the parties are not able to contract around the redistributive effect of those rules. Thus, the argument goes, legal rules can perform a meaningful redistributive function only in situations involving non-contract-based rules, such as tort rules governing the conduct of strangers ( that is, individuals not in a contractual relationship with one another). In general, with some significant qualifications, we agree that the haphazardness and contracting-around arguments provide a basis for generally preferring the tax-and-transfer system as the primary means of reducing income inequality

Revisiting the Roles of Legal Rules and Tax Rules in Income Redistribution: A Response to Kaplow & Shavell

The debate over whether legal rules should be used to redistribute resources in society or whether redistribution should be left exclusively to the tax-and-transfer system has long occupied philosophers, political theorists, economists, and legal academicians. For many years, the conventional wisdom on this question among legal scholars seemed to be that blanket generalizations were inappropriate. All systems of redistribution distort individuals\u27 choices and entail administrative costs. Therefore, the argument went, a universal preference for using the tax-and-transfer system to redistribute is not justified. Rather, the choice among institutions to accomplish society\u27s redistributive goals was considered to be an empirical one which must be resolved on a case-by-case basis, in the light of detailed information about the circumstances likely to influence the effectiveness of each method of redistribution. At some point, however, a contrary view developed among economists, a view that has become the new conventional wisdom: that income (or wealth) redistribution is always better accomplished through the tax-andtransfer system than through the legal system. One of the arguments traditionally offered to support this view is that redistribution through the legal system is by nature more haphazard (in the sense of less comprehensive and less precise) than redistribution through the tax system. That is, the tax system can redistribute from all better-off to all worse-off individuals, whereas the legal system can redistribute only from those better off to those worse off who are subject to the legal rule in question. In addition, it was often argued that the legal system\u27s capacity for income redistribution is, in any event, small because redistributive legal rules will be effective only in settings in which the parties are not able to contract around the redistributive effect of those rules. Thus, the argument goes, legal rules can perform a meaningful redistributive function only in situations involving non-contract-based rules, such as tort rules governing the conduct of strangers ( that is, individuals not in a contractual relationship with one another). In general, with some significant qualifications, we agree that the haphazardness and contracting-around arguments provide a basis for generally preferring the tax-and-transfer system as the primary means of reducing income inequality