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Efficient information searching and retrieval methods are needed to navigate the ever increasing volumes of digital information. Traditional lexical information retrieval methods can be inefficient and often return inaccurate results. To overcome problems such as polysemy and synonymy, concept-based retrieval methods have been developed. One such method is Latent Semantic Indexing (LSI), a vector-space model, which uses the singular value decomposition (SVD) of a term-by-document matrix to represent terms and documents in k-dimensional space. As with other vector-space models, LSI is an attempt to exploit the underlying semantic structure of word usage in documents. During the query matching phase of LSI, a user's query is first projected into the term-document space, and then compared to all terms and documents represented in the vector space. Using some similarity measure, the nearest (most relevant) terms and documents are identified and returned to the user. The current LSI query matching method requires that the similarity measure be computed between the query and every term and document in the vector space. In this paper, the kd-tree searching algorithm is used within a recent LSI implementation to reduce the time and computational complexity of query matching. The kd-tree data structure stores the term and document vectors in such a way that only those terms and documents that are most likely to qualify as nearest neighbors to the query will be examined and retrieved. 相似文献
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语义矢量空间模式（SVSM）及其试验评价——自然语言处理与文献自动标引 总被引：4，自引：0，他引：4
Ｇｅｏｆｒｅｙ Ｚ．Ｌｉｕ 《情报学报》1996,(6)
本文介绍一种基于句法分析和格式语义结构，被称为“语义矢量空间模式”的文献自动标引／检索技术。在此模式中，自然语言文献和检索提问均表示为语义矩阵。通过计算语义矩阵的相似值，检索系统可以预测文献与给定提问之间的相关度，从而达到检索相关文献的目的。初步试验结果表明，若文献及检索提问较长，特别是以原文献作为提问样本时，此检索技术与康奈尔大学的ＳＭＡＲＴ系统相比，在检全率、检准率和相关排序有效性方面均有所改进 相似文献
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基于潜语义标引的自然语言检索 总被引：3，自引：0，他引：3
在信息检索中, 向量空间模型是最有效的数学工具之一。由于自然语言检索的特殊性, 以及传统信息检索模型受到同义词、多义词的影响, 检索的查准率不高。为了提高自然语言检索的查准率, 我们对基于概念的信息检索模型——
潜语义标引(LS I) 模型进行了探讨, 并分析了基于LS I 的两个实例。 相似文献
潜语义标引(LS I) 模型进行了探讨, 并分析了基于LS I 的两个实例。 相似文献
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分析潜在语义索引的基本原理及其特点。针对LSI的3个因素，从特征词的选取，维数约简，特征词权重3个方面进行约定和改进。并以计算机类的科技文献作为测试文档，对改进的权重算法和改进前后LSI系统的检索结果进行分析。结果显示，特征词的选择结果及检索效果都得到较大的提高，性能稳定。 相似文献
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隐含语义检索及其应用 总被引：5，自引：1，他引：4
隐含语义检索(Latent Semantic Indexing, LSI) 是一种基于概念的文献检索方式。它区别于传统的基于用户查询条件与文档的单词匹配的文献检索方法, 根据文档与查询条件在语义上的关联而向用户提交查询结果。本文介绍了隐含语义检索在文献检索中的一种实现方法, 为文献检索提供了一种新的途径。 相似文献
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基于概念向量空间的文档语义分类模型研究 总被引：1，自引：0，他引：1
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Bing Bai Jason Weston David Grangier Ronan Collobert Kunihiko Sadamasa Yanjun Qi Olivier Chapelle Kilian Weinberger 《Information Retrieval》2010,13(3):291-314
In this article we present Supervised Semantic Indexing which defines a class of nonlinear (quadratic) models that are discriminatively
trained to directly map from the word content in a query-document or document-document pair to a ranking score. Like Latent
Semantic Indexing (LSI), our models take account of correlations between words (synonymy, polysemy). However, unlike LSI our
models are trained from a supervised signal directly on the ranking task of interest, which we argue is the reason for our
superior results. As the query and target texts are modeled separately, our approach is easily generalized to different retrieval
tasks, such as cross-language retrieval or online advertising placement. Dealing with models on all pairs of words features
is computationally challenging. We propose several improvements to our basic model for addressing this issue, including low
rank (but diagonal preserving) representations, correlated feature hashing and sparsification. We provide an empirical study
of all these methods on retrieval tasks based on Wikipedia documents as well as an Internet advertisement task. We obtain
state-of-the-art performance while providing realistically scalable methods. 相似文献
8.
一个构造良好的查询是信息检索质量的基本保证,语义查询扩展技术解决了传统信息检索系统不能很好理解用户查询意图的问题,在提高检索查全率的同时保证了检索准确率。本文以查询关键字之间的语义关联为切入点,辅以隐式反馈技术获取消歧上下文,以WordNet本体库和WordNet Domains扩展库作为消歧数据源,使用基于局部上下文和基于图论的两类无导词义消歧方法进行查询关键字到本体概念的映射,最后基于概念词汇关联完成基于语义的查询扩展。综合WordNet本体库和WordNet Domains扩展库中的各项知识源对查询词义进行判定,保证了词义消歧的精度;采用无导词义消歧实现查询词义的快速判定,保证了信息检索的实时性;根据查询关键词的多寡分别提出两类消歧方法,满足了各种查询需求。 相似文献
9.
基于个体概念语义关系的微内容发现研究 总被引：1，自引：0，他引：1
传统的超文本标记语言只能显示而不能使计算机理解页面信息,导致传统的基于关键词的检索工具的查准率、查全率和智能化程度都较低.虽然语义网可以解决计算机对页面信息的理解问题,但以往基于本体的语义匹配算法通常是面向类概念的,在精度上不能满足微内容的发现需求.本文面向微内容检索应用,在分析了个体概念的语义特征的基础上,提出了基于语义关系的个体匹配规则、索引结构和相应的语义检索算法.最后,通过实验验证,证明了基于个体语义关系的聚合机制具有更高的聚合细腻度,所提出的语义检索算法在面向微内容的检索应用中是有效的. 相似文献
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语义网的核心理念是使人和软件代理能够获取基于语义的信息，而语义门户是语义网的组成单元，是实现具有共同兴趣目标的人群之间的信息交流和共享的平台。SEAL是开发语义门户的一种与领域无关的方法，为门户中信息供给、信息获取、门户创建与维护等挖掘语义信息。本文主要从SEAL核心方法、体系结构、核心模块及核心模块的应用等几个角度进行了详细的介绍，以便为国内语义门户的研究提供一些参考。 相似文献
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计算机自动语义分析是当前制约自然语言信息检索、信息抽取与机器翻译等应用技术发展的一个瓶颈问题.语义角色标注是语义分析的一种主要实现方式,而目前语义角色的自动标注主要采用基于统计的方法,由于训练数据的规模有限、语义角色类型多,面临严重的数据稀疏问题,处理结果一致性差.本文则采取基于规则的方法,选择汉语框架语义知识库(CFN)所提供的框架和框架元素作为语义标注体系,利用CFN的语义标注句子库,根据短语类型、句法功能以及短语内部构成和外部语境等其他句法语义特征分析框架元素的实现规律,构建语义标注规则,经测试取得了令人满意的结果,为解决语义分析问题探索了一条可行的路线. 相似文献
14.
基于多层次概念语义网络结构的中文医学信息语义标引体系和语义检索模型研究 总被引：18，自引：0，他引：18
为了提高中文医学信息检索效率,本文应用语义学研究成果,深入剖析统一医学语言系统(UMLS),从理论上对多层次概念语义网络结构进行了探讨,以此设计了适用于中文医学信息特点的三层概念语义网络结构,并分别确定了各个概念语义网络层次的语义类型和语义关系,进一步完善了医学信息语义网络.以信息检索的认知理论为依据,建立了基于三层概念语义网络结构的中文医学信息语义标引体系和语义检索模型.对扩展检索和语义检索进行统计学Kappa检验,认为两种检索方法的一致性非常显著(p<0.01);与扩展检索中的任何一种方法相比,语义检索方法具有更高的检索效率. 相似文献
15.
基于IIG和LSI组合特征提取方法的文本聚类研究 总被引：8，自引：0，他引：8
本文利用改进的信息增益特征选择方法和潜在语义索引技术组合的特征提取方法 ,对文本进行了有效的自动聚类。从语料库中抽取了 2 5 0篇文本 ,首先利用向量空间模型和改进的信息增益特征选择方法 ,构造文本特征向量 ,利用C 均值方法聚类 ,聚类结果准确率、查全率、F measure分别达到 0 .82、0 . 88、0 .83。在此基础上 ,对最优的特征选择结果运用潜在语义索引方法 ,对奇异值分解的结果进行截断处理 ,发现奇异值K取 4 0时聚类结果的准确率、查全率、F measure达到 0 . 95、0. 5 7、0 . 78,在有效地降维的同时 ,大幅度地提高了聚类的准确率。 相似文献
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This paper describes a method, using Genetic Programming, to automatically determine term weighting schemes for the vector
space model. Based on a set of queries and their human determined relevant documents, weighting schemes are evolved which
achieve a high average precision. In Information Retrieval (IR) systems, useful information for term weighting schemes is
available from the query, individual documents and the collection as a whole.
We evolve term weighting schemes in both local (within-document) and global (collection-wide) domains which interact with
each other correctly to achieve a high average precision. These weighting schemes are tested on well-known test collections
and are compared to the traditional tf-idf weighting scheme and to the BM25 weighting scheme using standard IR performance metrics.
Furthermore, we show that the global weighting schemes evolved on small collections also increase average precision on larger
TREC data. These global weighting schemes are shown to adhere to Luhn’s resolving power as both high and low frequency terms
are assigned low weights. However, the local weightings evolved on small collections do not perform as well on large collections.
We conclude that in order to evolve improved local (within-document) weighting schemes it is necessary to evolve these on
large collections. 相似文献
18.
个性化语义TRIZ构建研究 总被引：2，自引：1，他引：1
[目的/意义]研究构建个性化语义TRIZ的方法、流程与关键技术.该语义TRIZ可对专利中隐性技术信息进行深度揭示与语义关联.[方法/过程]设计一个开放性语义TRIZ框架.该框架从概念空间、索引空间、应用空间3个维度构建语义TRIZ;从微观层SAO、中观层技术主题、宏观层技术范畴3个层面描述语义TRIZ索引结构.基于该框架,以大口径光学元件专利为例构建领域个性化语义TRIZ.[结果/结论]针对中等规模专利数据集(数千条),本方法能有效地半自动构建领域个性化语义TRIZ,支持专利深度技术挖掘应用. 相似文献
19.
This paper investigates the effectiveness of using MeSH® in PubMed through its automatic query expansion process: Automatic Term Mapping (ATM). We run Boolean searches based on a collection of 55 topics and about 160,000 MEDLINE® citations used in the 2006 and 2007 TREC Genomics Tracks. For each topic, we first automatically construct a query by selecting keywords from the question. Next, each query is expanded by ATM, which assigns different search tags to terms in the query. Three search tags: [MeSH Terms], [Text Words], and [All Fields] are chosen to be studied after expansion because they all make use of the MeSH field of indexed MEDLINE citations. Furthermore, we characterize the two different mechanisms by which the MeSH field is used. Retrieval results using MeSH after expansion are compared to those solely based on the words in MEDLINE title and abstracts. The aggregate retrieval performance is assessed using both F-measure and mean rank precision. Experimental results suggest that query expansion using MeSH in PubMed can generally improve retrieval performance, but the improvement may not affect end PubMed users in realistic situations. 相似文献
20.
Relevance feedback methods generally suffer from topic drift caused by word ambiguities and synonymous uses of words. Topic drift is an important issue in patent information retrieval as people tend to use different expressions describing similar concepts causing low precision and recall at the same time. Furthermore, failing to retrieve relevant patents to an application during the examination process may cause legal problems caused by granting an existing invention. A possible cause of topic drift is utilizing a relevance feedback-based search method. As a way to alleviate the inherent problem, we propose a novel query phrase expansion approach utilizing semantic annotations in Wikipedia pages, trying to enrich queries with phrases disambiguating the original query words. The idea was implemented for patent search where patents are classified into a hierarchy of categories, and the analyses of the experimental results showed not only the positive roles of phrases and words in retrieving additional relevant documents through query expansion but also their contributions to alleviating the query drift problem. More specifically, our query expansion method was compared against relevance-based language model, a state-of-the-art query expansion method, to show its superiority in terms of MAP on all levels of the classification hierarchy. 相似文献