Asymmetric Missing-data Problems: Overcoming the Lack of Negative Data in Preference Ranking

In certain classification problems there is a strong a asymmetry between the number of labeled examples available for each of the classes involved. In an extreme case, there may be a complete lack of labeled data for one of the classes while, at the same time, there are adequate labeled examples for the others, accompanied by a large body of unlabeled data. Since most classification algorithms require some information about all classes involved, label estimation for the un-represented class is desired. An important representative of this group of problems is that of user interest/preference modeling where there may be a large number of examples of what the user likes with essentially no counterexamples.Recently, there has been much interest in applying the EM algorithm to incomplete data problems in the area of text retrieval and categorization. We adapt this approach to the asymmetric case of modeling user interests in news articles, where only labeled positive training data are available, with access to a large corpus of unlabeled documents. User modeling is here equivalent to that of user-specific document ranking. EM is used in conjunction with the Naive Bayes model while its output is also utilized by a Support Vector Machine and Rocchio's technique.Our findings demonstrate that the EM algorithm can be quite effective in modeling the negative class under a number of different initialization schemes. Although primarily just the negative training examples are needed, a natural question is whether using all of the estimated labels (i.e., positive and negative) would be more (or less) beneficial. This is important considering that, in this context, the initialization of the negative class for EM is likely not to be very accurate. Experimental results suggest that EM output should be limited to negative label estimates only.     

对提高高校文献传递服务效率与质量的思考

本文阐述了高校图书馆文献传递服务工作发展的现状,分析了文献传递服务存在的问题,提出了提高文献传递服务质量的具体措施。     

XML文档相似度计算方法研究

XML(可扩展标记语言)正在成为Web上各种应用交换信息的标准.随着XML格式的半结构数据的大量出现,如何处理和管理XML文档已经成为了一个研究热点.XML文档的相似度计算是XML数据处理的重要课题,是XML文档聚类与检索的关键技术.XML文档由逻辑结构(structure)和文本内容(content)构成,可以根据结构特征或内容特征来度量XML文档之间的相似度.本文将XML文档的相似度计算方法分为基于结构的和结构与内容相结合的两类,并对各种已有的XML文档相似度计算方法进行了比较和述评.     

Structural technological direction in AIS design for regional analytical services

Results are presented, which were acquired by the author during research and development activities on the design, adaptation, introduction and elaboration of automated information systems of different types and purposes used in a variety of technologies for planning and making managerial decisions, namely: national corporate STI information centers, departmental systems of management (DSM), scientific production associations, firm analysis systems (FAS), and information analytical services at the federal and regional levels.     

Current research issues and trends in non-English Web searching

With increasingly higher numbers of non-English language web searchers the problems of efficient handling of non-English Web documents and user queries are becoming major issues for search engines. The main aim of this review paper is to make researchers aware of the existing problems in monolingual non-English Web retrieval by providing an overview of open issues. A significant number of papers are reviewed and the research issues investigated in these studies are categorized in order to identify the research questions and solutions proposed in these papers. Further research is proposed at the end of each section.

对科技查新工作中的问题及对策的探讨

对查新工作发展现状、存在问题及研究动态进行概括和分析,提出对策、建议.     

Management of a School of Library and Information Studies

No abstract available for this article.     

A Nosegay of Splendid Serials

No abstract available for this article.     

试论高校档案管理工作

高校档案管理是学校日常管理工作的一个重要组成部分,作者认为要有效地提高高校档案利用率,高校档案管理工作要创新、要与时俱进,尤其是要搞好信息时代的电子档案的管理工作。     

典范初成：西汉儒学文献的发展与演变

西汉是儒学文献体系初具的时期。一方面因惠帝＂除挟书之律＂、武帝＂置写书之官＂、成帝遣使＂求遗书于天下＂,前代经典文献大量复出,为后世形成＂七经＂、＂九经＂甚至＂十三经＂打下了文献基础,也为汉世＂罢黜百家,表彰六经＂准备了条件。另一方面,由于重儒和五经博士设立,儒家经典传授形成固定模式,大量解经文献涌现,在先秦旧有＂传记＂之外,西汉产生了许多反映经学＂家法＂的＂章句＂文献;也由于儒学及其经典得到重视,西汉还产生了神化儒学的＂谶纬＂文献。章句和谶纬在西汉曾经盛行一时,但终因太过曲学阿世和唯利是趋,而缺学术价值和传世价值,最终都退出历史舞台,消失在历史的尘埃之中。