Data skeletons: simultaneous estimation of multiple quantiles for massive streaming datasets with applications to density estimation

We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic. We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation. For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation study to perform well and to have several distinct advantages over existing methods.     

情境在古诗词教学中的作用

情境教学法在古诗词教学中有重要作用,通过拓宽教育空间、缩短心理距离、注重角色效应、领悟诗词谐趣等四种途径可以增强情境教学的效果。     

Constrained allocation problems with single-peaked preferences: An axiomatic analysis

We introduce a new class of problems that contains two existing classes: allocation problems with single-peaked preferences and bankruptcy problems. On this class, we analyze the implications of well-known properties such as Pareto optimality, strategy-proofness, resource-monotonicity, no-envy, equal treatment of equals, and two new properties we introduce, hierarchical no-envy and independence of nonbinding constraints. Unlike earlier literature, we consider rules that allow free-disposability. We present characterizations of a rule we introduce on this domain. We relate this rule to well-known rules on the aforementioned subdomains. Based on this relation, we present a characterization of a well-known bankruptcy rule called the constrained equal awards rule. Received: 22 June 2000/Accepted: 21 March 2002 This paper is based on the first chapter of my Ph.D. thesis submitted to the University of Rochester. I wish to thank my advisor, William Thomson, for helpful comments and suggestions.     

当前我国区域经济发展差距

随着改革开放的不断深入 ,我国区域经济发展的差距日益拉大 ,已经成为社会广泛关注的热点问题。从缩小我国区域经济发展差距的必要性入手 ,分析了我国区域经济发展差距的产生原因 ,并就新形势下如何尽快缩小我国区域经济差距问题 ,提出了看法     

中国城市化道路模式探讨

改革开放以来,我国城市化进程明显加快,进入到加速发展的新时期。但长期实施的城市化方针却严重阻碍了我国城市化向更高层次的迈进。积极发展小城镇并非是适合我国城市化进程的选择,大城市的快速发展是城市化进程中不可阻挡的潮流,我国的城市化进程中大城市的发展应得到充分重视。