基于领域本体知识库的语义查询扩展

为了在检索过程中全面表达用户查询意图,提出了基于领域本体知识库的语义查询扩展方法。该方法借助领域本体推理出的知识,使检索系统从语义层面理解用户查询语句,并通过语义相似度来控制扩展词的规模,避免了查询过度扩展,使得新构造的查询能更准确地描述用户的检索需求,提高了检索的有效性。原型系统的实验结果表明,该方法较传统的关键字匹配法和LAC方法有明显的优势,在保障查全率的基础上,可极大地提高检索准确率。     

基于概念图的信息检索的查询扩展模型

针对传统的基于关键词匹配的信息检索存在的查全率和精确率不高的问题,提出一种基于概念图匹配的查询扩展方法：一方面通过知网对用户查询的词或者句子进行扩展后,将用户查询和文档生成概念图;另一方面利用概念图的不完全匹配和语义相似度的计算方法计算概念图的相似度,以提高检索效果。实验结果表明该方法取得了良好的效果。     

基于扩展查询表达式的XML关键字查询

目前可扩展标示语言(XML)关键字查询大多是基于最小公共祖先(LCA)语义子树产生查询结果,而未能加入除LCA语义子树之外与用户查询意图相关的结果。为解决该问题,提出一种基于扩展查询表达式的XML关键字查询方法。将用户查询日志作为查询扩展统计模型,对其进行统计分析,并结合最佳检索概念判断是否需要扩展查询表达式。使用XML TF-IDF方法计算候选属性的权重,根据初检结果的上下文信息,利用聚类方法获得与查询意图最相关的扩展查询关键字,从而扩展查询表达式。实验结果表明,与XSeek和基于语义词典的查询扩展方法相比,该方法的平均F度量值分别提高了7%和17%,具有较高的查询质量。     

一种针对特定领域的查询扩展方法

为提高特定领域信息检索的效率,针对用户的查询需求不能准确、清晰地表述查询意图的问题,提出一种基于领域本体的语义查询扩展算法。该算法结合领域本体中知识库和实例库的特点,设计相应的扩展算法。其中,基于知识库的扩展主要依赖于等价关系、父类关系和子类关系等层次结构关系。基于实例库的扩展方法主要有:数值型属性扩展和基于统计的语义字典的文本型属性扩展。最后,利用实验验证语义扩展算法的有效性和可行性,并与相关研究方法进行比较,表明该方法在查全率、查准率上也取得了较好的效果。     

教学资源概念查询扩展研究

查询扩展是在原查询词的基础上加入与用户查询词相关的词或者词组,组成新的、更准确的查询序列,使扩展后的查询序列能更清晰地表达用户的查询请求,克服自然语言的“二义性”。基于《计算机网络》概念语义网络能更加有效地找出计算机网络领域内查询词的概念词及扩展概念词,并向上拓展将各个查询词的原始语义关系联接起来,解决了查询词之间缺乏联系的问题,为扩展检索的实现奠定基础。描述了概念语义网络的生成方法、关联概念树的抽取方法和查询扩展检索的计算机实现流程,为教学资源领域的在线学习提供了技术支持。     

基于隐马尔可夫模型的查询扩展方法

对查询进行扩展的目的是找出查询中的潜在语义,确定用户意图,进而构造更适合于搜索引擎检索的查询语句,以提高检索的准确率。提出利用隐马尔可夫模型预测查询中的潜在语义的方法,该模型在大规模用户查询日志上进行训练。由该模型预测出的扩展语句查询的准确率较词共现扩展、同义词扩展等方案均有明显提升。     

基于权重查询词的XML结构查询扩展

文本文档信息检索中检索质量不高的一个主要原因是用户难以提出准确的描述查询意图的查询表达式. 而XML文档除了具有文本文档的内容特征外,还具有结构特征,导致用户更难以提出准确的查询表达式.为了解决这一问题,提出一种基于相关反馈的查询扩展方法,可以帮助用户构建满足查询意图的"内容 结构"的查询表达式.该方法首先进行查询词扩展,找到最能代表用户查询意图的权重扩展查询词;然后在扩展查询词的基础上进行结构查询扩展;最终形成完整的"内容 结构"的查询扩展表达式.实验结果表明,与未进行查询扩展相比,扩展后prec@10和prec@20的平均准确率提高30%以上.     

语义检索系统中的查询语句扩展算法改进

查询扩展技术是在原有用户查询的基础上加入语义相关的新词,组成语义更准确的查询条件。文中对查询扩展算法中扩展词加权方法进行改进,提出一种基于初始用户查询意欲和词与词间语义关联性给扩展词加权的方法。根据此算法得到的扩展词权值不仅反映了该扩展词和原关键词间的关联性,还反映出该扩展词和查询关键词集合中所有元素的关联性。因此,可将基于语义树的查询扩展问题转换为扩展词权值wijs,o,p的计算,如何计算出权值wijs,o,p是文中的核心。实验证明,该算法提高了检索的查准率。     

语义检索系统中的查询语句扩展算法改进

查询扩展技术是在原有用户查询的基础上加入语义相关的新词,组成语义更准确的查询条件.文中对查询扩展算法中扩展词加权方法进行改进,提出一种基于初始用户查询意欲和词与词间语义关联性给扩展词加权的方法.根据此算法得到的扩展词权值不仅反映了该扩展词和原关键词间的关联性,还反映出该扩展词和查询关键词集合中所有元素的关联性.因此,可将基于语义树的查询扩展问题转换为扩展词权值wiis,o,p的计算,如何计算出权值wijs,o,p是文中的核心.实验证明,该算法提高了检索的查准率.     

一种改进了的查询扩展算法

在进行检索的时候,用户给出的查询关键字常常不能准确地表达出用户的真实意图,所以要对用户的查询关键字进行扩展。该文章改进了基于本体的查询关键字扩展算法,加入了反映与用户意图符合程度的贴近度系数以及扩展短语对文本重要程度的隶属度系数。经实验证实,改进后的算法在查全率和查准率方面有明显的提高。     

中文文本的信息自动抽取和相似检索机制

目前信息抽取成为提供高质量信息服务的重要手段,提出面向中文文本信息的自动抽取和相似检索机制,其基本思想是将用户兴趣表示为语义模板,对关键字进行概念扩充,通过搜索引擎获得初步的候选文本集合,在概念触发机制和部分分析技术基础上,利用语义关系到模板槽的映射机制,填充文本语义模板,形成结构化文本数据库.基于文本数据表述的模糊性,给出用户查询与文本语义模板的相似关系,实现了相似检索,可以更加全面地满足用户的信息需求.     

用户需求概念图的生成方法研究

网络信息检索在当前互联网社会得到了广泛应用,但是其检索准确性却不容乐观,究其原因是割裂了检索关键词之间的概念联系。从一类限定领域的用户需求入手,以搜索引擎作为网络语料资源的访问接口,综合利用规则与统计的方法,生成查询需求的语义概念图。可将其作为需求分析的结果,导引后续的语义检索过程,提高用户查询与返回结果的相关性。实验结果表明,生成方法是有效可行的,对基于概念图的语义检索有一定的探索意义。     

Enriching the conceptual basis for query formulation through relationship semantics in databases

The rapid increase in end-user computing calls into question the suitability of existing database query languages (DBQLs). Because the typical DB end-user is not a DB specialist, it is essential that DBQLs use concepts that are as close as possible to those in the end-users’ cognitive mental model and adopt interface techniques that are suited to end-users’ abilities. Concept-based query languages are well suited for this. This realization has motivated further research in conceptual, or semantic, query approaches. However, the primary focus in this field has been on semantic query optimization, not on query formulation. In this study, we address ourselves to the problem of formulation of queries using concepts. We propose a concept-based query language, called the conceptual query language (CQL), which allows for the conceptual abstraction of database queries and exploits the rich semantics of data models to ease and facilitate query formulation.The CQL approach uses the relationship semantics of semantic data models to render transparent the technical complexities of existing DB query languages. Association semantics are also used to automatically construct query graphs and pseudo-natural language explanations of queries, and to generate SQL codes. A set theoretic formalism for conceptual queries is developed and used. This paper discusses the design of CQL, its expressive power, its implementation, and the strategies for CQL query processing. The implementation of a CQL prototype is briefly discussed in this paper. User experiments were carried out extensively and showed the advantage of CQL over alternative languages such as SQL.     

Translation of fuzzy queries for relational database system

The concept of a database skeleton which reflects both the user's conception of the real world and the system's understanding of the interrelationships among database entities is described. It consists of a conceptual schema (conceptual graphs) and a relational schema (information graph). With the aid of the database skeleton, fuzzy queries can be translated and disambiguated by analyzing the queries using the conceptual graphs of a database skeleton. The query language XQL is introduced, and the XQL translator is described in some detail.     

基于加权SimRank的中文查询推荐研究

查询推荐是搜索引擎系统中的一项重要技术,其通过推荐更合适的查询以提高用户的搜索体验。现有方法能够找到直接通过某种属性关联的相似查询,却忽略了具有间接关联的语义相关查询。该文将用户查询及查询间直接联系建模为查询关系图,并在图结构相似度算法SimRank的基础上提出了加权SimRank (简称WSimRank)用于查询推荐。WSimRank综合考虑了查询关系图的全局信息,因而能挖掘出查询间的间接关联和语义关系。然而,WSimRank复杂度太高而难以实用,该文将WSimRank转换为一个状态层次图的遍历和计算过程,进而采用动态规划、剪枝等策略对其进行优化从而可以实际应用。在大规模真实Web搜索日志上的实验表明, WSimRank在各项评价指标上均优于SimRank和传统查询推荐方法,其MAP指标接近0.9。     

A visual query language for graphical interaction withschema-intensive databases

This paper presents a visual query language called VQL for interacting with an object-oriented schema-intensive data model. VQL allows convenient access to the various types of knowledge captured by the semantic model. It consists of a set of “graphical primitives” along with a combination grammar for creating graphical queries. The visual language is internally supported by a prolog-like predicate based query language. The formal grammar underlying the predicate based language is also presented. Apart from being able to create simple queries that can be specified in SQL or QBE, VQL can be used for making queries on any object-oriented data model including the generalization of the E-R model. VQL also handles complicated, indirect queries, specially those that require a reasoning system for query interpretation and response generation. Further, recursive queries on graph structures such as finding transitive closures of graphs may be easily specified. Perhaps the most powerful feature of VQL is its ability to provide high semantic expressibility (in being able to specify highly complex queries) while maintaining simplicity in the user's query formulation process. VQL is embedded in an object-oriented graphical database interaction environment that supports schema creation and manipulation in addition to database querying and updation. The prototype has been implemented in Smalltalk-80 running on a Sun 3/60 workstation. All the illustrations of visual interaction presented are taken from actual interaction sessions     

基于MPEG-7的视频语义检索系统

设计和实现一个支持语义的分布式视频检索系统:"语寻"。该系统利用一个改进的视频语义处理工具(该工具基于IBM VideoAnnEx标注工具,并增加镜头语义图标注和自然语言处理的功能)对视频进行语义分析和标注,生成包含语义信息的MPEG-7描述文件,然后对视频的MPEG-7描述文件建立分布式索引,并同时分布式存储视频文件;系统提供丰富的Web查询接口,包括关键字语义扩展查询,语义图查询以及自然语句查询,当用户提交语义查询意图后,便能够迅速地检索到感兴趣的视频和片段,并且可以浏览点播;整个系统采用分布式架构,具备良好的可扩展性,并能够支持海量视频信息的索引和检索。     

Towards Intelligent Semantic Caching for Web Sources

An intelligent semantic caching scheme suitable for web sources is presented. Since web sources typically have weaker querying capabilities than conventional databases, existing semantic caching schemes cannot be directly applied. Our proposal takes care of the difference between the query capabilities of an end user system and web sources. In addition, an analysis on the match types between a user's input query and cached queries is presented. Based on this analysis, we present an algorithm that finds the best matched query under different circumstances. Furthermore, a method to use semantic knowledge, acquired from the data, to avoid unnecessary access to web sources by transforming the cache miss to the cache hit is presented. To verify the effectiveness of the proposed semantic caching scheme, we first show how to generate synthetic queries exhibiting different levels of semantic localities. Then, using the test sets, we show that the proposed query matching technique is an efficient and effective way for semantic caching in web databases.     

Generating queries and replies during information-seeking interactions

Analysis of naturally occurring information-seeking dialogues indicates that they usually consist of a number of distinct discourse segments, such as a greeting segment, a request issued by a user, an optional clarification segment, a transfer of information segment and a final closing segment. The clarification interaction is often initiated by the information provider and it may be due to one of the following reasons: (1) there is confusion regarding the user's intentions, (2) there is insufficient information to formulate a plan to satisfy a recognized intention, or (3) there is difficulty in formulating a plan that satisfies a recognized intention. Once the information provider determines the user's intention and formulates a plan to achieve this intention, the information transfer phase is initiated to inform the user about the proposed plan.In this paper, we present a mechanism for generating queries during the clarification stage and answers during the information transfer stage. Given a hierarchical representation of the alternatives possibly intended by a user and the probabilities of these alternatives, our mechanism determines the hierarchy level at which a query must be directed and the query to be posed in order to determine the alternative intended by the user. Once the user's intentions are ascertained, the mechanism determines whether additional information is required and the manner in which queries may be posed to acquire this information. When a user's intentions cannot be satisfied by means of a single plan, our mechanism enters into a negotiation process to alter the user's specifications until a valid plan is formulated. In the final stages of the interaction, the mechanism determines the information to be transferred and generates an answer to effect the transfer. The mechanisms for negotiation and for the generation of queries and answers described in this paper have been implemented in a system called , a computerized information providing system that functions as a travel agent.     

基于语义向量表示的查询扩展方法

针对传统查询扩展方法在专业领域中扩展词与原始查询之间缺乏语义关联的问题,提出一种基于语义向量表示的查询扩展方法。首先,构建了一个语义向量表示模型,通过对语料库中词的上下文语义进行学习,得到词的语义向量表示;其次,根据词语义向量表示,计算词之间的语义相似度;然后,选取与查询中词汇的语义最相似的词作为查询的扩展词,扩展原始查询语句;最后,基于提出的查询扩展方法构建了生物医学文档检索系统,针对基于维基百科或WordNet的传统查询扩展方法和BioASQ 2014—2015参加竞赛的系统进行对比实验和显著性差异指标分析。实验结果表明,基于语义向量表示查询扩展的检索方法所得到结果优于传统查询扩展方法的结果,平均准确率至少提高了1个百分点,在与竞赛系统的对比中,系统的效果均有显著性提高。