On the difficulty of making social choices

The difficulty of making social choices seems to take on two forms: one that is related to both preferences and the method used in aggregating them and one which is related to the preferences only. In the former type the difficulty has to do with the discrepancies of outcomes resulting from various preference aggregation methods and the computation of winners in elections. Some approaches and results which take their motivation from the computability theory are discussed. The latter institution-free type of difficulty pertains to solution theory of the voting games. We discuss the relationships between various solution concepts, e.g. uncovered set, Banks set, Copeland winners. Finally rough sets are utilized in an effort to measure the difficulty of making social choices.     

品牌基础问题研究评述

品牌问题一直是国际营销学术界的研究热点领域。对文献总结发现,在品牌基础问题的理论和方法研究中,主要集中在品牌认识、品牌选择和品牌发展3个方面。国内外研究者从不同的理论出发运用不同方法解释了品牌的认识、选择和发展,主要是分别从消费者和企业2个角度来分析和探讨品牌问题,但是缺乏二者之间互动关系的研究,使得品牌基础问题的研究不能为企业品牌创建、品牌战略和品牌延伸提供合理建议。     

A likelihood ratio test to discriminate exponential–Poisson and gamma distributions

The exponential–Poisson (EP) distribution with scale and shape parameters β>0 and λ∈?, respectively, is a lifetime distribution obtained by mixing exponential and zero-truncated Poisson models. The EP distribution has been a good alternative to the gamma distribution for modelling lifetime, reliability and time intervals of successive natural disasters. Both EP and gamma distributions have some similarities and properties in common, for example, their densities may be strictly decreasing or unimodal, and their hazard rate functions may be decreasing, increasing or constant depending on their shape parameters. On the other hand, the EP distribution has several interesting applications based on stochastic representations involving maximum and minimum of iid exponential variables (with random sample size) which make it of distinguishable scientific importance from the gamma distribution. Given the similarities and different scientific relevance between these models, one question of interest is how to discriminate them. With this in mind, we propose a likelihood ratio test based on Cox's statistic to discriminate the EP and gamma distributions. The asymptotic distribution of the normalized logarithm of the ratio of the maximized likelihoods under two null hypotheses – data come from EP or gamma distributions – is provided. With this, we obtain the probabilities of correct selection. Hence, we propose to choose the model that maximizes the probability of correct selection (PCS). We also determinate the minimum sample size required to discriminate the EP and gamma distributions when the PCS and a given tolerance level based on some distance are before stated. A simulation study to evaluate the accuracy of the asymptotic probabilities of correct selection is also presented. The paper is motivated by two applications to real data sets.     

Books on probability ideas are reviewed

In this paper, semiparametric methods are applied to estimate multivariate volatility functions, using a residual approach as in [J. Fan and Q. Yao, Efficient estimation of conditional variance functions in stochastic regression, Biometrika 85 (1998), pp. 645–660; F.A. Ziegelmann, Nonparametric estimation of volatility functions: The local exponential estimator, Econometric Theory 18 (2002), pp. 985–991; F.A. Ziegelmann, A local linear least-absolute-deviations estimator of volatility, Comm. Statist. Simulation Comput. 37 (2008), pp. 1543–1564], among others. Our main goal here is two-fold: (1) describe and implement a number of semiparametric models, such as additive, single-index and (adaptive) functional-coefficient, in volatility estimation, all motivated as alternatives to deal with the curse of dimensionality present in fully nonparametric models; and (2) propose the use of a variation of the traditional cross-validation method to deal with model choice in the class of adaptive functional-coefficient models, choosing simultaneously the bandwidth, the number of covariates in the model and also the single-index smoothing variable. The modified cross-validation algorithm is able to tackle the computational burden caused by the model complexity, providing an important tool in semiparametric volatility estimation. We briefly discuss model identifiability when estimating volatility as well as nonnegativity of the resulting estimators. Furthermore, Monte Carlo simulations for several underlying generating models are implemented and applications to real data are provided.     

THE RELEVANCE OF THE CONCEPT OF DISSOCIATION IN CHILD PROTECTION

This paper explores one aspect of unresolved trauma, namely dissociation. Its relevance to child protection is discussed with reference to two aspects: emotional neglect and choice of partner. There is an exploration of the implications for both assessment and treatment. The central place of shame in relation to dissociation is also explored. It is argued that dissociation is an important concept in child protection assessments and that social work assessments should be alert to this.     

吉伯德-萨特思韦特防策略不可能性定理的逻辑初探

自20世纪70年代吉伯德-萨特思韦特防策略不可能性定理确立后，引起了数学、经济学、计算机科学和哲学等诸多领域中学者的广泛关注。然而，在国内外文献中，对吉伯德-萨特思韦特防策略不可能性定理的逻辑研究还比较少。基于此，借助公理化的方法探讨吉伯德-萨特思韦特防策略不可能性定理，并形式化地给出定理的内容和证明，力图把精细的逻辑推理应用于复杂的过程分析中，使防策略投票这一过程形式化、清晰化，以期能指导人们进行合理、有效的决策活动。     

民汉双语诉讼规则之探索

我国宪法赋予了公民用自己的民族语言文字参加诉讼的权利，目的在于实现民族平等、促进民族团结、禁止民族分裂、保护中华民族语言文化的多样性，进而提高我国的文化软实力。通过调查民族语言文字诉讼司法实务，发现当前存在着少数民族语言文字诉讼程序混乱、不符合诉讼原理等问题，不利于民族语言文字诉讼权利的实现。究其原因，在于该诉讼制度缺乏程序保障。为了确保民族语言文字诉讼权利的有效实现，应设立“民汉双语诉讼规则”，以为司法机关提供统一的操作规范。民汉双语诉讼规则应该明确民汉双语诉讼的概念、类型以及民族语言文字诉讼权利的内容，并且根据不同诉讼类型有针对性地设置审判语言与诉讼语言的适用规则。     

慈善与慈善组织的秩序维度与政策选择

人是生活在秩序维度的，人的生命的价值，尤其是劳动力的价值，与处于不同秩序维度有关系。公共慈善也是如此。它有原始秩序的维度，也有扩展秩序的维度，在不同的维度里，有不同的价值。从特朗普家族慈善基金会的命运，可以见出慈善和慈善组织涉及到的不同维度秩序的冲突。更好地发展慈善和慈善组织，需要解决冲突，在不同的秩序维度里，处理好各个方面的关系。