An attempt to understand the four color problem

Is the recently obtained, computer-aided proof of the Four Color Theorem an isolated phenomenon or is its combinatorial complexity typical for a significantly large class of mathematical problems? While it is too early to give a definite answer to this question, an informal discussion is undertaken in this article.     

传统节会的声誉溢出效应:基于Kreps-Milgrom-Roberts-Wilson声誉模型

中国经济繁荣带来传统节会复苏,但是传统节会市场的鱼龙混杂导致传统节会声誉参差不齐,该现象引起了政府部门的重视和学术界的关注.现有文献侧重于对节会概念、意义、文化层面的讨论,缺乏对节会声誉问题的研究,因此本文参考Kreps-Milgrom-Roberts-Wilson声誉模型,在四个基本假设基础上建立了传统节会的声誉模型,分析了传统节会的声誉溢出效应及均衡条件.研究发现:第一,参与者认为传统节会承办方的声誉越好,承办方选择不欺骗参与者的概率就越大,承办方建立声誉的积极性也就越高;第二,一旦承办方出现欺骗参与者的行为,参与者就会认为其是弱承办方,在下一期承办方会失去参与者的信任,从而失去长期获利的机会;第三,无论是强承办方还是弱承办方,不去欺骗参与者才是最优选择,此时承办方和参与者可以实现合作共赢,这是一种更有效率的文化旅游发展模式.因此,文章提出了建立传统节会声誉评价制度与信息公开制度、加强对传统节会的监管以及完善相关法律法规的政策建议.     

Reputation,inequality and meeting techniques: visualising user hierarchy to support collaboration

Equality within groups is ordinarily taken for granted when technology for e-democracy is conceived and developed. However, inequality in online communication is just as common as in other social contexts. Therefore, we have developed a groupware with the express purpose of illuminating imbalance of power. Inequalities are measured and made visible to users of the system, and they change dynamically as actions are taken by users. The system is based on democratic meeting techniques and is reminiscent of a strategy game based on social media. Each participant’s score within the game is dynamically calculated and reflects that user’s activity, others’ reactions to that activity and reactions to others’ activities. The calculations and weighing mechanisms are open to inspection and change by the users, and hierarchical roles reflecting game levels may be attached to system rights belonging to individual users and user groups. The prototype we present stems from the question of how to conceive of groupware based on diversity and is the result of combining social theory with algorithms for modelling and visualising user hierarchy and status. Empirical user tests suggest improvements to the prototype’s interface, which will be implemented and further evaluated by embedding the algorithms in a system for e-participation.     

Exploring communication networks to understand organizational crisis using exponential random graph models

In recent social network studies, exponential random graph (ERG) models have been used comprehensively to model global social network structure as a function of their local features. In this study, we describe the ERG models and demonstrate its use in modelling the changing communication network structure at Enron Corporation during the period of its disintegration. We illustrate the modelling on communication networks, and provide a new way of classifying networks and their performance based on the occurrence of their local features. Among several micro-level structures of ERG models, we find significant variation in the appearance of A2P (Alternating k-two-paths) network structure in the communication network during crisis period and non-crisis period. We also notice that the attribute of hierarchical positions of actors (i.e., high rank versus low rank staff) have impact on the evolution process of networks during crisis. These findings could be used in analyzing communication networks of dynamic project groups and their adaptation process during crisis which could lead to an improved understanding how communications network evolve and adapt during crisis.     

声誉效应与经理报酬契约的关系研究

探讨了声誉对经理报酬契约的影响 .首先 ,分析了经理效用函数的组成 ,将声誉这个隐性激励约束因素引入经理的效用函数 .随后 ,建立了信息不对称下经理的报酬激励模型 .分析了声誉系数对契约中各要素的影响 ,说明了所有者可以利用经理的声誉效应来设计更加有利的报酬契约 .文章最后给出了主要结论 .     

Using scatterplots to understand and improve probabilistic models for text categorization and retrieval

The two-dimensional representation of documents which allows documents to be represented in a two-dimensional Cartesian plane has proved to be a valid visualization tool for Automated Text Categorization (ATC) for understanding the relationships between categories of textual documents, and to help users to visually audit the classifier and identify suspicious training data. This paper analyzes a specific use of this visualization approach in the case of the Naive Bayes (NB) model for text classification and the Binary Independence Model (BIM) for text retrieval. For text categorization, a reformulation of the equation for the decision of classification has to be written in such a way that each coordinate of a document is the sum of two addends: a variable component P(d|c_i), and a constant component P(c_i), the prior of the category. When plotted in the Cartesian plane according to this formulation, the documents that are constantly shifted along the x-axis and the y-axis can be seen. This effect of shifting is more or less evident according to which NB model, Bernoulli or multinomial, is chosen. For text retrieval, the same reformulation can be applied in the case of the BIM model. The visualization helps to understand the decisions that are taken to order the documents, in particular in the case of relevance feedback.     

基于信誉机制的加权秘密共享方案

针对传统秘密共享总是基于参与者的权力或地位分配权重的问题,考虑参与者的信誉值,把参与者的权重值与其信誉值联系起来,基于信誉值对参与者的权重进行重新分配,提出了基于信誉机制的权重分配函数,并以此为基础构建了一个基于信誉机制的加权秘密共享方案,分析表明重构算法中的重构邀请机制可以有效地促使参与者同意送行秘密重构,并且方案可以有效为每个参与者分配权重.     

中介服务机构的信誉评估模型

本文利用综合模糊评判方法针对中介服务机构的信誉评估问题 ,给出了一个综合评估模型 .     

C2C模式下卖家信誉建立与提升策略研究

当前信誉已成为电子商务发展中不可回避的问题.C2C模式下,信誉是交易进行的基础,它直接关系着交易的安全有效.从卖家收益的视角出发,运用博弈理论分析了C2C模式下卖家信誉的演化过程,提出了惩罚和信任两种策略的适用条件.结果表明对于新进入的卖家,发表承诺和买方的惩罚能够促使其建立信誉,而对于已具有一定信誉值的卖家而言,买家的充分的信任和积极评价将是其维持和提升信誉的动力来源.     

全社会资金运行的多元统计分析

本文首先利用聚类分析、时差相关分析、K -L信息量等方法 ,以国内生产总值发展速度的波动曲线为基准循环曲线对各种经济指标进行分类和筛选 ,从而选定先行、一致 ,滞后三类指标组 ,然后运用主成分分析方法编制景气指数 ,得到先行、一致、滞后三类指标数 ,并结合我国改革开放以来的经济周期波动的实际 ,对所得到的景气指数进行分析 ,结果比较令人满意。     

隐性约束机制的设计研究

文章研究在多阶段动态博弈情况下隐蔽行为的隐性约束机制设计问题，用博弈论方法和信息经济学的委托-代理理论方法，建立多阶段委托-代理关系约束问题重复博弈的声誉模型，对隐蔽行为的隐性约束机制进行研究，证明了多阶段委托-代理关系中隐性约束机制的存在，给出了这种情况下的有效约束条件，隐性约束机制的设计方法以及其他结论。     

Modeling Reputation Management System on Online C2C Market

This paper discusses the effectiveness of sharing information concerning the reputations of buyers and sellers making online transactions in a consumer-to-consumer (C2C) market. We developed a computer simulation model that describes online transactions with a reputation management system that shares information concerning the reputations of consumers. The model takes an agent-based approach in which agents' actions are based on the iterated prisoner's dilemma. No model exists to analyze C2C markets even though there are many case studies concerning the effectiveness of sharing reputation information among participants in a market. The simulation results revealed that a positive reputation system can be more effective than a negative reputation system for an online transaction, even though the negative one can work for a traditional transaction. The result should be an important consideration when designing practical reputation management systems for online transactions.     

An innovative multistage, physiologically structured, population model to understand the European grapevine moth dynamics

We present a multistage, physiologically structured, population model for studying the dynamics of one of the most important grapevine insect pests. Growth of the population at each stage is modeled considering the climatic variations and the grape variety. A result of existence and uniqueness of solutions is presented for this original hyperbolic system as well as simulations of experimental field data.