Computing tournament solutions using relation algebra and RelView

We describe a simple computing technique for the tournament choice problem. It rests upon relational modeling and uses the BDD-based computer system RelView for the evaluation of the relation-algebraic expressions that specify the solutions and for the visualization of the computed results. The Copeland set can immediately be identified using RelView’s labeling feature. Relation-algebraic specifications of the Condorcet non-losers, the Schwartz set, the top cycle, the uncovered set, the minimal covering set, the Banks set, and the tournament equilibrium set are delivered. We present an example of a tournament on a small set of alternatives, for which the above choice sets are computed and visualized via RelView. The technique described in this paper is very flexible and especially appropriate for prototyping and experimentation, and as such very instructive for educational purposes. It can easily be applied to other problems of social choice and game theory.     

科学家之路：从博士研究生到诺贝尔物理学奖得主

分析了诺贝尔物理学奖获奖者的年龄结构与学位制度,获奖工作与博士学位论文的关系以及导师对获奖者的作用.认为获奖者博士阶段的学习和研究工作是其成为一流科学家的关键阶段.     

Rankings aggregation in regional planning

This paper proposes a solution to the Owsinsky and Zadrozny problem based on the Condorcet criterion. With this unique criterion and a unique approach it is possible to obtain either a collective ranking or clusters without using any distance. In both cases indices of conditioning can be associated. Also in both cases a very simple way (requiring practically no computation for this problem) to obtain the collective results will be given.     

How mathematical impossibility changed welfare economics: A history of Arrow's impossibility theorem

During the 20th century, impossibility theorems have become an important part of mathematics. Arrow's impossibility theorem (1950) stands out as one of the first impossibility theorems outside of pure mathematics. It states that it is impossible to design a welfare function (or a voting method) that satisfies some rather innocent looking requirements. Arrow's theorem became the starting point of social choice theory that has had a great impact on welfare economics. This paper will analyze the history of Arrow's impossibility theorem in its mathematical and economic contexts. It will be argued that Arrow made a radical change of the mathematical model of welfare economics by connecting it to the theory of voting and that this change was preconditioned by his deep knowledge of the modern axiomatic approach to mathematics and logic.     

组合拍卖在门户网站广告机会分配中的应用

目前门户网站的广告机会销售主要通过价格协商的方式,这种方式不仅导致大量的中间交易成本而且分配结果常常无法达到最优.针对该情形,本文结合门户网站广告机会的特点,建立了广告机会分配的组合拍卖模型.该模型能让广告主自由的表达广告机会之间的无差异及互补效用.通过将该模型的特例转化为一般背包问题,文中证明了该问题求解的NP难特性.因此本文针对标的本身的结构提出了四种启发式信息及两种求解器:二元蚁群算法及贪婪算法.最后通过数值实验给出了在不同情况下,不同启发信息的性能并表明了在任何情况下二元蚁群算法比贪婪算法的寻优性更强.     

公平性与数学化(Ⅰ)选举理论

作者在这一系列文章中,将用不多的数学知识讨论由公平性问题派生出来的三个社会学课题：即选举理论,权力指数与公平分配。数学家的研究可以归结为这么一个结论：社会选择,一个难圆的梦。本篇讨论各种常用选举方法的利弊,并由此讨论选举理论中的一个重要的结果——Ａｒｒｏｗ定理：完全公平的选举系统不可能存在     

Min-Max payoffs in a two-player location game

We consider a two-player, sequential location game with arbitrarily distributed consumer demand. Players alternately select locations from a feasible set so as to maximize the consumer mass in their vicinity. Our main result is a complete characterization of feasible market shares, when locations form a finite set in R^d.     

Condorcet efficiency and constant scoring rules

Exact closed form relations are obtained for the Condorcet efficiencies of the four constant scoring rules on three element rankings when all profiles of rankings are assumed to be equally likely to occur. The Condorcet efficiencies of the two stage constant rules are shown to be substantially greater than those of single stage constant rules. The single stage scoring rule that picks the element that is ranked first most often is shown to have a much greater efficiency than the single stage scoring rule that selects the element that has the fewest last place rankings.     

The Condorcet criterion and committee selection

Recent studies have evaluated election procedures on their propensity to select committees that meet a Condorcet criterion. The Condorcet criterion has been defined to use majority agreement from voters' preferences to compare the selected committee to all other committees. This study uses a different definition of the Condorcet criterion as defined on committees. The focus of the new definition is on candidates. That is, we consider majority agreement on each candidate in the selected committee as compared to each candidate not in the selected committee.This new definition of the Condorcet criterion allows for the existence of majority cycles on candidates within the selected committee. However, no candidate in the non-selected group is able to defeat any candidate in the selected committee by majority rule. Of particular interest is the likelihood that a committee meeting this Condorcet criterion exists. Attention is also given to the likelihood that various simple voting procedures will select a committee meeting this Condorcet criterion when one does exist.     

Approaches to collective decision making with fuzzy preference relations

Recent experimental studies show that the predictive accuracy of many of the solution concepts derived from the collective decision making theory leaves much to be desired. In a previous paper the author attempted to explain some of the inaccuracies in terms of the fuzzy indifference regions of the individuals participating in the voting game. This paper gives straightforward generalizations of the solutions concepts in terms of the fuzzy social or individual preference relations. It turns out that some of these new solution concepts cotain their nonfuzzy counterparts as subsets. Others, in turn, are subsets of their nonfuzzy counterparts. We also discuss a method of aggregating individual nonfuzzy preferences so as to get a fuzzy social preference relation and, furthermore, a nonfuzzy social choice set.