Bounding Optimal Expected Revenues for Assortment Optimization under Mixtures of Multinomial Logits

We consider assortment problems under a mixture of multinomial logit models. There is a fixed revenue associated with each product. There are multiple customer types. Customers of different types choose according to different multinomial logit models whose parameters depend on the type of the customer. The goal is to find a set of products to offer so as to maximize the expected revenue obtained over all customer types. This assortment problem under the multinomial logit model with multiple customer types is NP‐complete. Although there are heuristics to find good assortments, it is difficult to verify the optimality gap of the heuristics. In this study, motivated by the difficulty of finding optimal solutions and verifying the optimality gap of heuristics, we develop an approach to construct an upper bound on the optimal expected revenue. Our approach can quickly provide upper bounds and these upper bounds can be quite tight. In our computational experiments, over a large set of randomly generated problem instances, the upper bounds provided by our approach deviate from the optimal expected revenues by 0.15% on average and by less than one percent in the worst case. By using our upper bounds, we are able to verify the optimality gaps of a greedy heuristic accurately, even when optimal solutions are not available.     

落实最严格水资源管理的适应性政策选择研究

由于最严格水资源管理存在着水资源供给、用水总量、用水关系和用水管理等诸多不确定,采用可操作的实施就成为落实最严格水资源管理的关键。研究发现:(1)通过最严格水资源管理的压力—状态—响应(PSR)分析可知,最严格水资源管理的实施路径与水资源适应性管理在目标理念、工作途径、核心问题和保障需求方面有着一致性;(2)水资源适应性政策选择能够促进最严格水资源管理的有效落实,为此给出了适应性政策选择程序,为最严格水资源管理落实的政策选择提供参考依据。     

居民出行方式选择影响因素的研究述评

居民出行方式选择事关家庭能源消费,对于节能减排目标实现具有重要影响。基于个体、群体两个对象,从主观、客观两个视角梳理了居民出行方式选择行为的主要影响因素,并深入阐明了各影响因素的概念、相互联系及作用机制。研究发现,目前该领域的研究趋势正在由主观因素转变到客观因素,从个体因素转变到群体因素,且存在以下不足之处:若干心理变量的解释和作用机制仍存在争议;缺乏行为的社会网络构建和扩散分析;过度依赖经典的“刺激-反应”行为主义模式和“成本-收益”的理性决策架构;缺乏由行为到态度等心理变量的逆向反馈分析。未来应结合中国国情,通过系统学和社会网络的方法探究居民出行方式选择的动机、实施、强化、约束、反馈、路径及扩散等动态过程,并引入实验法来加强引导政策的研究。     

浅埋大跨黄土隧道下穿公路方案比选

以大跨黄土隧道下穿公路安全施工为背景,对隧道下穿公路的安全施工方案进行研究。基于公路路面破损指数与下穿公路施工风险事件引起路面最大沉降之间的关系确定了隧道下穿施工可能引起的路面最大允许沉降量,并据此制定出施工管理基准,对比分析了CRD和CD法引起的隧道拱顶沉降、地表最大沉降、支护受力和隧道周边地层塑性区特征,建议采用CD法进行下穿施工。下穿孙辛路施工监测结果表明,采用CD法保证了隧道施工安全和孙辛路的正常通行。     

财政调控的价值定位、方式创新及法治化路径

近期财政部出台的法治财政建设实施方案将宏观调控的创新方式借用于财政领域,提出财政面向上的区间调控、定向调控、相机调控、精准调控和适时预调微调等,体现出财政的工具主义价值。从形式上来看,这与当下公共财政时代所要求的规范主义价值,存在着阶段性目标追求的二律背反,但基于财政有效治理的国家任务,两者又统一于良法善治的终极价值属性之中。对于仍深受财政工具主义思维禁锢的当下中国而言,更应提倡的是财政的规范主义价值,防止偏重调控结果有效而轻视调控过程正义,从遵循调控法定、尊重市场规则和坚持民生导向的路径出发,以期实现在调控权力控制下的国家全面可持续性发展。     

城市八零后家长择园观的调查及评析

择园问题已经成为目前的教育热点与社会热点问题,而时代特征明显的八零后一代已经成为新一代家长,其受教育程度不断提高,对幼儿教育也越来越重视,对幼儿入园问题也愈加关注。调查显示:城市八零后家长择园观存在较大差异和一定的误区,而通过引导家长树立正确的教育观、正确认识幼儿园保教关系、掌握正确的择园策略,可为家长科学择园提供指导。     

分析马克思主义的方法论基础探析

分析马克思主义作为西方马克思主义研究的一种新范式而出现,实现了马克思主义研究的方法论的新突破.西方社会科学中流行的个人主义解释模式构成其方法论的学术背景.约翰·埃尔斯特构建出分析马克思主义方法论的框架--以方法论个人主义为方法论原则,以意向性解释尤其是理性选择理论、博弈论为具体解释方法.围绕方法论个人主义和理性选择理论的争论逐步凸显出分析马克思主义研究方法论的全貌.只有运用辩证法精神,才能恰当处理方法论个人主义与方法论集体主义的关系、理性选择理论与功能解释的关系,才能准确评判与把握分析马克思主义的方法论基础.     

“经济人”:一种研究范式的革新与局限

公共选择理论的“经济人”研究范式主要包括经济人假设、交易政治学和方法论的个人主义三部分。通过对这种范式的私益内涵分析和利弊分析,指出其在革新传统政治学研究方法的同时也具有自身不可克服的局限。借鉴“经济人”研究范式对我国政治学乃至经济学研究都具有重要的方法论意义。     

Cultural capital or relative risk aversion? Two mechanisms for educational inequality compared1

In this paper we empirically examined two explanatory mechanisms for educational inequality: cultural reproduction and relative risk aversion, using survey data taken from secondary school pupils in Amsterdam. Cultural reproduction theory seeks to explain class variations in schooling by cultural differences between social classes. Relative risk aversion theory argues that educational inequalities can be understood by between-class variation in the necessity of pursuing education at branching points in order to avoid downward mobility. We showed that class variations in early demonstrated ability are for a substantial part cultural: cultural capital - measured by parental involvement in highbrow culture - affected school performance at the primary and secondary level. However, relative risk aversion - operationalized by being concerned with downward mobility - strongly affects schooling ambitions, whereas cultural capital had no effect. Thus, we conclude that 'primary effects' of social origin on schooling outcomes are manifested through cultural capital and not through relative risk aversion (in addition to other potential sources of class variations such as genetics). Relative risk aversion, and not cultural capital, affects schooling ambitions, which is relevant for our understanding of secondary effects.     

会计职业判断与会计政策选择问题

会计政策的选择过程实质上也是职业判断的过程,为此在探讨会计职业判断与会计政策选择关系的基础上,围绕着如何利用会计职业判断优化会计政策选择展开论述。