常见英语错误缘说

我国常见英语错误的发生率之高和涉及面之广已成为建设和谐社会的一道煞风景.本文通过对实际错误病例的列举并逐一对导致错误的缘由进行解说,兼辅以据出权威出版物的更正,以正视听.     

英美法上的要物合同机制及其启示

关于我国民法典中要物合同的存废,英美法上的要物合同机制可带来不少启示。英美法的经验所传递的信息是,要物合同被确立下来依赖于其无偿的人际关系的产生背景,正是在此基础上,它适用＂没有给就没有还＂的法律逻辑。它被保留下来,很大程度上是法律传统使然。进一步分析,还可以补充上法律目的与法律伦理等方面的理由。在对待要物合同的问题上,建议以前述理由为据,保留无偿的传统要物合同,将有偿要物合同予以诺成化改造。     

英语试卷的编排

要让学生考出真实水平 ,有很多因素可以促成这一目标的达到 ,其中一个因素为试卷的编排。试卷的编排涉及到试卷的总体编排和试卷题目各部分的编排。编排顺序或方式不当皆可导致分数的无效差异 ,所以应引起注意。     

可数集类的共性集

讨论了有限集类在增补集合的情况下同阶共性集的相互联系，有限集类的共性集与可数集类的共性集之间的极限关系，得出了可数事件的共性事件概率公式．     

基于“木桶原理”视野下的集体运动项群

在木桶原理的视角下,通过分析影响集体运动项群运动成绩的多种因素,找出在多因素当中会对运动成绩影响较大的短板因素;发现弱项和及时补短.让多种因素协调发展,这对提高团队运动成绩具有重要意义.     

计算最大Lyapunov指数的推广小数据量法

在分析常用的计算最大Lyapunov指数小数据量法的基础上,研究了混沌吸引子时间轨道的不可逆特性,提出基于后向搜索和双向搜索计算最大Lyapunov指数的推广小数据量法通用经验公式。数值仿真表明,新方法比原来仅做前向搜索的小数据量法在计算准确度和抗噪声性能上更加优越。     

建立规范的投资管理体制

加强投资前期管理,完善投资管理过程,是保证投资决策成功,避免资金浪费,提高经济效益的一条有效途径。本文论述了投资管理体系的内容及具体实施方法。     

Estimating the number of clusters

Hartigan (1975) defines the number q of clusters in a d ‐variate statistical population as the number of connected components of the set {f > c}, where f denotes the underlying density function on R^d and c is a given constant. Some usual cluster algorithms treat q as an input which must be given in advance. The authors propose a method for estimating this parameter which is based on the computation of the number of connected components of an estimate of {f > c}. This set estimator is constructed as a union of balls with centres at an appropriate subsample which is selected via a nonparametric density estimator of f. The asymptotic behaviour of the proposed method is analyzed. A simulation study and an example with real data are also included.     

Tractable Consideration Set Structures for Assortment Optimization and Network Revenue Management

Discrete‐choice models are widely used to model consumer purchase behavior in assortment optimization and revenue management. In many applications, each customer segment is associated with a consideration set that represents the set of products that customers in this segment consider for purchase. The firm has to make a decision on what assortment to offer at each point in time without the ability to identify the customer's segment. A linear program called the Choice‐based Deterministic Linear Program (CDLP) has been proposed to determine these offer sets. Unfortunately, its size grows exponentially in the number of products and it is NP‐hard to solve when the consideration sets of the segments overlap. The Segment‐based Deterministic Concave Program with some additional consistency equalities (SDCP+) is an approximation of CDLP that provides an upper bound on CDLP's optimal objective value. SDCP+ can be solved in a fraction of the time required to solve CDLP and often achieves the same optimal objective value. This raises the question under what conditions can one guarantee equivalence of CDLP and SDCP+. In this study, we obtain a structural result to this end, namely that if the segment consideration sets overlap with a certain tree structure or if they are fully nested, CDLP can be equivalently replaced with SDCP+. We give a number of examples from the literature where this tree structure arises naturally in modeling customer behavior.