A note on the existence of unique equivalent martingale measures in a Markovian setting

Simple sufficient conditions for the existence of a unique equivalent martingale measure are provided. Furthermore, these conditions give us a handle on situations where an equivalent martingale measure cannot exist. The existence of a unique equivalent martingale measure is of relevance to problems in mathematical finance. Two examples of models for which the question of existence was unresolved are studied. By means of our results existence of a unique equivalent measure up to an explosion time is proved.     

试论生态林业系统的时空观

生态林业系统具有时间、空间两个序列的开发前景。长周期,大跨度的生态林业生产可以分解为复合的短周期方式,使生态意识与经济效益有机结合。空间组合的多层次立体开发有效地利用了光、热、水、土资源,并获得最大生物量;地域组合着眼宏观,注重研究大型骨干及网络性生态工程问题。     

Working-time reduction and employment: experiences in Europe and economic policy recommendations

The paper seeks to evaluate the evidence on the employment effectsof the collective working-time reductions in Europe over thepast 20 years. While theoretical analyses produce contradictoryassessments, most empirical studies show positive employmenteffects but take insufficient account of these conditions underwhich the reductions in working time were implemented. Theseconditions for the success of collective working-time reductionsinclude an active training policy designed to minimise skillshortages in the labour market, the modernisation of work organisation,wage increases in conjunction with productivity gains and amore equal income distribution.     

营销角度的特许经营及其竞争法上的思考

特许经营是一种新型的销售方式,作为企业分销系统的构成要素,能够起到降低风险,沟通生产与消费的作用。然而在实际经营过程中也会出现许多诸如指定购买与搭售、联合定价、独占经营等违反竞争法的问题。为适应不断变化的竞争形势,应从竞争法的层面上对其加以规制。     

On optimality in intergenerational risk sharing

Summary. This paper defines and studies optimality in a dynamic stochastic economy with finitely lived agents, and investigates the optimality properties of an equilibrium with or without sequentially complete markets. Various Pareto optimality concepts are considered, including interim and ex ante optimality. We show that, at an equilibrium with a productive asset (land) and sequentially complete markets, the intervention of a government may be justified, but only to improve risk sharing between generations. If markets are incomplete, constrained interim optimality is investigated in two-period lived OLG economies. We extend the optimality properties of an equilibrium with land and give conditions under which introducing a pay-as-you-go system at an equilibrium would not lead to any Pareto improvement. Received: October 5, 1998; revised version: April 3, 2001     

收购兼并在上市公司发展战略中的地位和实施策略

本文主要阐述了以下三个方面的问题：（1）公司为何及时从事购并交易；（2）如何使购并活动获得成功；（3）制定中国进行购并行动的战略。     

基于延迟自相关特性的码速率测量技术

通信信号的识别与解调是通信侦察的重要研究内容，在通常情况下，通信信号的很多参数并不知道。本文介绍了一种基于通信信号码延迟自相关特性的码速率测量技术，并给出了码速率测量理论分析及基于硬件的实现技术，仿真和实验结果表明本方案具有较高的测量性能。     

中国农村金融组织生存、变迁及发展

由于农业的弱质性及在国民经济发展中的基础地位，农村金融组织在农村经济及整个国民经济稳定发展中发挥着不可或缺的作用。中国农村金融组织也有一个生存、发展的制度变迁过程。本文在研究了合作经济及农村金融组织在农村经济发展中的作用的基础上，重点研究了法国的农村金融体系在法国国民经济中的作用，并进一步探讨了中国农村金融组织的生存条件、制度变迁及发展。     

关于健全独立董事制度的若干思考

入世给我国中小企业的发展带来了机遇与挑战。培育核心竞争力是其抓住机遇 ,应对挑战 ,走向成功的关键所在。文章在分析了我国中小企业面临困境的基础上 ,提出了培育我国中小企业核心竞争力 ,促进我国中小企业发展的方法和措施。     

高校隐性德育资源的开发与建设

隐性德育问题是当前德育问题的重要前沿性课题。随着德育学科的科学发展以及教育的现代化趋势,重视并充分利用隐性德育资源促进高校大学生的全面发展,已经成为当前高校德育(或思想政治教育)改革的一个重要趋势。在高校中,隐性德育是相对显性德育而言的,是高校整体德育的有机组成部分,隐性德育资源对学生的发展起到潜移默化的影响和塑造作用。本文从高校隐性德育资源的内涵、开发与建设的原则和途径等方面进行阐述,意在引起对高校隐性德育资源的重视,合理开发和建设。