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本文就倒排档检索中的核心环节——检索提问式的逆波兰转换,提出了一种崭新的算法——二项拆分法,从逻辑式自身的性质出发,避开了常用的福岛法的判断算子优先级别的弊端,巧妙地实现了逆波兰转换,并在C—dBASEⅡ上得到了实现。 相似文献
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优化倒排文档检索算法 总被引：1，自引：0，他引：1
目前,国内对倒排文档的检索大多采用福岛法,以及在此基础上的一系列优化算法,如:预处理法[1]、准逆波兰变换法[2]、逆波兰回溯算法(RPRSA)[3]等.这些算法固然优化了福岛算法,却未能完全克服福岛法本身的缺陷. 相似文献
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本文针对《计算机情报检索的新算法及其在C—dBASEⅢ上的实现》一文中的可以避开算子优先级别的讨论实现逆波兰算法的观点提出了不同看法。然后提出了一种逆波兰算法的改进算法——括号加权法,并在dBASEⅢ、Fox Base和Fox Pro上得到了实现,证明是可行和高效的算法。 相似文献
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研究了一套改进的基于XML架构的关系数据映射索引机制。针对DTD不足,设计了XML Schema算法,完成了关系数据向XML模式的完全转换,并在映射后的XML文档OEM树上运用了一种新的逆波兰链索引技术,同时利用Hash表存储结点指针,实现了查询处理代价的最小化O（n）。 相似文献
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介绍数据结构学科中的一个重要领域——后缀表达式（逆波兰式）的求法。通过栈的应用、标识符树、扩号转换三种方法讨论后缀表达式实现方法以及它们的适用范围。 相似文献
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介绍数据结构学科中的一个重要领域——后缀表达式(逆波兰式)的求法。通过栈的应用、标识符树、扩号转换三种方法讨论后缀表达式实现方法以及它们的适用范围。 相似文献
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《军工科研院所军转民科技开发与技术转移研究》课题组 《科研管理》1993,(5):21-26
本文在大量调查研究的基础上,就军工科研院所转换运行机制,实现军民结合的模式选择问题进行了研究,分析了“亦军亦民”和“一所两制”两种结合模式利弊。 相似文献
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查全率-查准率间存在顺变关系的数学证明 总被引：7，自引：0，他引：7
本文从理论上利用数学推导方法对查全率与查准率之间的关系进行了推导、论证，得出：不同的检索条件下，查全率与查准率之间可以呈现出逆变、顺变或不变的关系；并给出呈现不同关系时的条件关系式。文中同时对现有方面中仅得出“查全率－查准率互逆相关”结论的原因进行了剖析。 相似文献
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In this paper, a new source selection algorithm for uncooperative distributed information retrieval environments is presented. The algorithm functions by modeling each information source as an integral, using the relevance score and the intra-collection position of its sampled documents in reference to a centralized sample index and selects the collections that cover the largest area in the rank-relevance space. Based on the above novel metric, the algorithm explicitly focuses on addressing the two goals of source selection; high-recall, which is important for source recommendation applications and high-precision which is important for distributed information retrieval, aiming to produce a high-precision final merged list. 相似文献
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We study several machine learning algorithms for cross-language patent retrieval and classification. In comparison with most of other studies involving machine learning for cross-language information retrieval, which basically used learning techniques for monolingual sub-tasks, our learning algorithms exploit the bilingual training documents and learn a semantic representation from them. We study Japanese–English cross-language patent retrieval using Kernel Canonical Correlation Analysis (KCCA), a method of correlating linear relationships between two variables in kernel defined feature spaces. The results are quite encouraging and are significantly better than those obtained by other state of the art methods. We also investigate learning algorithms for cross-language document classification. The learning algorithm are based on KCCA and Support Vector Machines (SVM). In particular, we study two ways of combining the KCCA and SVM and found that one particular combination called SVM_2k achieved better results than other learning algorithms for either bilingual or monolingual test documents. 相似文献
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Taxonomy is widely used in many of the website and directory navigation schemes for content/knowledge retrieval. However, information or content navigation support through taxonomy is often constrained due to its inability to take into account the full nomenclature and cultural nuances of knowledge seekers. The emergence and increasing adoption of collaborative tagging (social bookmarking) tools have provided lightweight and informal conceptual structures called folksonomies for knowledge retrieval. As for folksonomies, they reflect the vocabulary of the users. Hence, integrating folksonomies into a taxonomy combines the best of the two schemes as the resultant structure enhances taxonomy navigation with personsalisation for knowledge search and retrieval. This paper presents TaxoFolk, an algorithm for deriving hybrid taxonomy-folksonomy classification for enhanced knowledge navigation. The algorithm integrates folksonomy with a taxonomy through several unsupervised data mining techniques with augmented heuristics. 相似文献
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Collaborative information retrieval involves retrieval settings in which a group of users collaborates to satisfy the same underlying need. One core issue of collaborative IR models involves either supporting collaboration with adapted tools or developing IR models for a multiple-user context and providing a ranked list of documents adapted for each collaborator. In this paper, we introduce the first document-ranking model supporting collaboration between two users characterized by roles relying on different domain expertise levels. Specifically, we propose a two-step ranking model: we first compute a document-relevance score, taking into consideration domain expertise-based roles. We introduce specificity and novelty factors into language-model smoothing, and then we assign, via an Expectation–Maximization algorithm, documents to the best-suited collaborator. Our experiments employ a simulation-based framework of collaborative information retrieval and show the significant effectiveness of our model at different search levels. 相似文献
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在文本检索过程中充分利用词语之间的上下文关系有助于提高检索性能.首先对已有的相关工作进行综述;然后针对已有研究对词语上下文关系应用不足的现状,提出一种基于词语上下文关系的文本检索算法;最后通过实验对该算法进行验证. 相似文献
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采用在HSV彩色空间的色调累积直方图和边缘直方图分别表示颜色和形状特征,进行相似性检索,并结合综合权重调整的相关反馈技术来满足用户的检索需求。实验结果表明,此算法能获得有效的检索效果。 相似文献
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基于情报检索的汉语同义词识别初探 总被引：3，自引：0，他引：3
随着计算机的飞速发展，自然语言越来越广泛地应用于情报检索，同义词控制问题也成为情报学的研究热点。本文提出一种识别同义词的方法，这种方法基于检索网络搜索得到的统计数据，使用Dice测度方法测量两个词的相关度，相关度在给定的阈值内就可以认为是同义词。通过分析测试结果，验证这种方法的可行性，并提出了这种方法的优缺点及其应用。 相似文献
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《Information processing & management》2001,37(5):741-761
In the information retrieval systems, one of the most important and difficult operations is to extract appropriate keywords from documents. This paper proposes an effective substring search method by extending a pattern matching machine for multi-keyword based on Aho and Corasick (AC) called AC machine. The proposed method enables us to extract keyword candidates as much as possible and to select the suitable keywords for users' purpose at a retrieval stage. This method contains four types of substring search methods (exact, prefix, suffix and proper substring search). This paper also proposes a construction algorithm of the retrieval structure for speeding up the substring search. From the simulation results, it is shown that the retrieval time of the presented method is as fast as the key retrieval method based on the trie. 相似文献