Implementation in perfect equilibria

This paper considers implementation when the feasible outcomes are lotteries over a finite set of alternatives. The following weak condition is sufficient for implementation in trembling hand perfect equilibria (with three or more players): if all but one player agree on which alternative is the best, this alternative is (among those that are) chosen by the social choice rule, and if all but one player agree on which alternative is the worst, this alternative is not chosen. Many interesting social choice rules that are not Nash implementable satisfy this condition. On the other hand, there are social choice rules that are implementable in Nash equilibria but not in perfect equilibria.I am grateful to Luis Corchón, Eric Maskin, William Thomson, seminar participants at Harvard and Rochester, and two anonymous referees for helpful comments and suggestions. This research was supported by grants from the Royal Swedish Academy of Sciences and the Bank of Sweden Tercentenary Foundation.     

Probabilistic allocation rules and single-dipped preferences

We consider the problem of allocating an infinitely divisible endowment among a group of agents with single-dipped preferences. A probabilistic allocation rule assigns a probability distribution over the set of possible allocations to every preference profile. We discuss characterizations of the classes of Pareto-optimal and strategy-proof probabilistic rules which satisfy in addition replacement-domination or no-envy. Interestingly, these results also apply to problems of allocating finitely many identical indivisible objects – to probabilistic and to deterministic allocation. Received: 23 November 1998/Accepted: 20 October 2000     

Subgame perfect implementation of voting rules via randomized mechanisms

We characterize completely ordinal and onto choice rules that are subgame perfect of Nash equilibrium (SPE) implementable via randomized mechanisms under strict preferences. The characterization is very operationalizable, and allows us to analyse SPE implementability of voting rules. We show that no scoring rule is SPE implementable. However, the top-cycle and the uncovered correspondences as well as plurality with runoff and any strongly Condorcet consistent voting rule can be SPE implemented. Therefore our results are favourable to majority based voting rules over scoring rules. Nevertheless, we show that many interesting Condorcet consistent but not strongly Condorcet consistent rules, such as the Copeland rule, the Kramer rule and the Simpson rule, cannot be SPE implemented.     

Population monotonic rules for fair allocation problems

We consider the property of population monotonicity in the context of fair allocation problems in private good economies. It is already known that the property is compatible with the equal division lower bound. We show that if the equal division lower bound is replaced with no envy, the compatibility does not hold. We also show that the incompatibility persists even though no envy is weakened to no domination or -no domination. Hence, among the fairness criteria mentioned above, only the equal division lower bound is compatible with population monotonicity.This part of my dissertation thesis. I thank to my advisor William Thomson for many valuable comments. I also thank to Youngsub Chun and Yangkyu Byun for their comments. All remaining errors are, of course, mine.     

Sources of information and portfolio allocation

This research investigates the relationship between how a household receives financial information and the degree to which investment portfolios are diversified. Diversification is measured as allocation across asset classes and share of assets held in each asset class. Propensity score-based techniques incorporating stratification and weighting are employed to better isolate causal links, while also controlling for objective and subjective financial literacy and overconfidence. Results indicate that the use of financial planners and brokers is associated with an increase in asset class diversification. Households that consult with financial planners and bankers allocate their wealth systematically different from those who do not. These results highlight the role that financial professionals play in helping households make investment decisions.     

The reinforcement axiom under sequential positional rules

The reinforcement axiom roughly states that when an alternative is selected by two different constituencies, it must also be selected by their union. Hare and Coombs rules are special cases of sequential positional voting rules, which are known to violate this axiom. In this article, we first show that reinforcement can be violated by all such rules. We then evaluate, by the use of Monte Carlo simulations and the Fishburn–Gehrlein technique, the proportion of profiles at which this phenomenon occurs.     

Welfarist evaluations of decision rules under interstate utility dependencies

We provide welfarist evaluations of decision rules for federations of states and consider models, under which the interests of people from different states are stochastically dependent. We concentrate on two welfarist standards, viz. that the expected average utility for a person in the federation be maximized or that the expected utilities for the different people be equal. We discuss an analytical result that characterizes the decision rule with maximum expected average utility, set up a class of models that display interstate dependencies and run simulations for different dependency scenarios in the European Union. We find that the results that Beisbart and Bovens (Soc Choice Welf 29:581–608, 2007) established for two types of models without interstate dependencies are fairly stable if interstate dependencies are switched on. There are exceptions, though: sometimes the way in which alternative decision rules shape the welfare distribution is significantly affected by such dependencies. These exceptions particularly include cases in which the interests of people from different states are partly anti-correlated.     

Substitute-care information systems under public law 96-272

This paper reports on the results of a survey of state responses to the requirements of Public Law 96-272, including the use of permanency planning and periodic review techniques in substitutecare services, and, in particular, the nature and scope of information systems developed to monitor these services. Officials from 44 states and the District of Columbia completed the survey.All respondents reported having implemented statewide policies requiring permanency planning for and periodic review of all substitute-care cases. Those surveyed also indicated strongly favorable attitudes toward these policies among both administrators and direct-service personnel.A large majority (85%) of responding states had developed automated information systems for substitute care, most in the form of a central, statewide data base. Only four states reported depending solely on manual record keeping. The computer systems were most frequently used for administrative applications such as generating aggregate reports, monitoring case reviews, and coordinating caseloads. Applications least commonly reported included reducing narrative recording, determining placement availability, and linking clients to resources, activities more common to direct services. Finally, results of a set of attitudinal questions indicated support for the use of automated data management and the belief that it is a necessary technology, but many respondents also noted that automation has engendered complaints and opposition from staff members in field settings.     

Strategic, sincere, and heuristic voting under four election rules: an experimental study

We report on laboratory experiments on voting. In a setting where subjects have single-peaked preferences, we find that the rational choice theory provides very good predictions of actual individual behavior in one-round and approval voting elections but fares poorly in explaining vote choice under two-round elections. We conclude that voters behave strategically as far as strategic computations are not too demanding, in which case they rely on simple heuristics (under two-round voting) or they just vote sincerely (under single transferable vote).     

浅谈商品住宅装修一次到位

装饰装修是住宅产业的一个重要组成部分,全装修成品房是商品房发展的方向,世界各国都在极力倡导。随着人们生活水平的不断提高,家庭的装饰装修已走入千家万户,成为一种潮流。但是,由于相关行业管理相对滞后,家庭装修中出现了一些问题,如“游击队”作坊式装修,质量难以保证,管理失控,资源浪费等,特别是二次装修造成的破坏结构、扰民现象已成为公害。随着经济的发展及人民生活水平的不断提高,特别是加入WTO后,成品房将进一步取代毛坯房,成为住房市场的主流。因为住宅一次装修到位将成为国际化后的商品住宅市场的准入规则,也将为住宅装饰装修…     

Random conjugates of bankruptcy rules

This article introduces and analyzes random conjugates of bankruptcy rules. A random conjugate is a rule which is derived from the definition of the underlying rule for two-claimant problems. For example, the random conjugate of the Aumann–Maschler rule yields an extension of concede-and-divide: the basic solution for bankruptcy problems with two claimants. Using the concept of random conjugates an alternative characterization of the proportional rule is provided. It turns out that the procedural definition of a random conjugate extends several of the properties of the underlying rule for two-claimant problems to the general domain of problems with an arbitrary number of claimants.     

Queue allocation of indivisible goods

A model with a finite number of indivisible goods (houses) and the same number of individuals is considered. The allocation of houses among the individuals according to a queue order is analysed. First an allocation mechanism is constructed where it is a dominant strategy for the individuals to truthfully report their preferences. Second it is demonstrated that in order to obtain the desired allocation, the individuals must not in general report their complete ranking of the houses, but only their maximal elements in recursively defined choice sets.Financial support from Jan Wallander's Foundation for Research in the Social Sciences is gratefully acknowledged.A first version of this paper was presented at ESEM in Cambridge 1991.     

Subgame perfect implementation of stable matchings in marriage problems

We study a sequential matching mechanism, an extensive form game of perfect information, to implement stable matchings in marriage problems. It is shown that the SPE (subgame perfect equilibrium) of this mechanism leads to the unique stable matching when the Eeckhout (Econ Lett 69:1–8, 2000) condition for the existence of a unique stable matching holds. This result does not extend to preferences that violate the Eeckhout condition, even if the matching problem has a unique stable matching. We then introduce a weaker condition, called the α ^M condition, under which the SPE outcome of the men-move-first mechanism is the men-optimal stable matching. The α ^M condition is necessary and sufficient for the men-optimal stable matching to be Pareto optimal for men.     

Strategy-proof allocation of indivisible goods

Strategy-proof allocation of a finite number of indivisible goods among a finite number of individuals is considered. The main result is that in a pure distributional case, a mechanism is strategy-proof, nonbossy and neutral if and only if it is serially dictatorial. If the indivisible goods are initially owned by the individuals, a mechanism is strategy-proof, individually rational and Pareto consistent if and only if it is the core mechanism. Received: 15 September 1997/Accepted: 12 May 1998     

New characterizations of old bankruptcy rules

This paper presents axiomatic characterizations of two bankruptcy rules discussed in Jewish legal literature: the Constrained Equal Awards rule and the Contested Garment principle (the latter is defined only for two-creditor problems.) A major property in these characterizations is independence of irrelevant claims, which requires that if an individual claim exceeds the total to be allocated the excess claim should be considered irrelevant.The author gratefully acknowledges helpful conversations with Oscar Volij.     

Homotopy properties of Pareto aggregation rules

 We establish that the Pareto property is inconsistent with non-dictatorship for social choice rules defined on two-dimensional choice spaces. In addition, we consider applications of this result in higher dimensions. We also establish the existence of Pareto rules with infinite populations, and show that in this case there is a strong manipulator. Received: 30 December 1994/Accepted: 22 April 1996