Text document clustering using global term context vectors

Despite the advantages of the traditional vector space model (VSM) representation, there are known deficiencies concerning the term independence assumption. The high dimensionality and sparsity of the text feature space and phenomena such as polysemy and synonymy can only be handled if a way is provided to measure term similarity. Many approaches have been proposed that map document vectors onto a new feature space where learning algorithms can achieve better solutions. This paper presents the global term context vector-VSM (GTCV-VSM) method for text document representation. It is an extension to VSM that: (i) it captures local contextual information for each term occurrence in the term sequences of documents; (ii) the local contexts for the occurrences of a term are combined to define the global context of that term; (iii) using the global context of all terms a proper semantic matrix is constructed; (iv) this matrix is further used to linearly map traditional VSM (Bag of Words—BOW) document vectors onto a ‘semantically smoothed’ feature space where problems such as text document clustering can be solved more efficiently. We present an experimental study demonstrating the improvement of clustering results when the proposed GTCV-VSM representation is used compared with traditional VSM-based approaches.     

一种基于加权投票的术语自动识别方法

术语自动识别目的是获取领域术语表中未登录的规范化词汇,是信息抽取、文本挖掘等领域中的重要任务。近年来,利用统计方法抽取术语取得了一定进展,出现了C-Value、NC-Value、TermExtractor等有效方法。但是,对各种统计指标进行加权投票的方法研究较少。该文首先从大量已知术语中收集术语的词性模板,并借之抽取候选术语,接着利用了统计指标加权投票对这些候选术语进行排序。在IEEE 2006-2007电子工程领域文献上的实验结果表明,加权投票方法比任一单独指标的识别效果更好。     

融合共现距离和区分度的短文本相似度计算方法

针对短文本内容简短、特征稀疏等特点,提出一种融合共现距离和区分度的短文本相似度计算方法。一方面,该方法在整个短文本语料库中利用两个共现词之间距离计算它们的共现距离相关度。另一方面通过计算共现区分度来提高距离相关度的准确度,然后对每个文本中词项进行相关性加权,最后通过词项的权重和词项之间的共现距离相关度计算两个文本的相似度。实验结果表明,本文提出的方法能够提高短文本相似度计算的准确率。     

基于核心词项平均划分相似度的短文本聚类算法

针对短文本特征极度稀疏、上下文依赖性强等特点,以自顶向下的策略,提出一种基于核心词项平均划分相似度的短文本聚类算法CTMPS。该方法首先在整个短文本语料库中计算词项之间的概率相关性,以此为基础对短文本中词项进行加权,将权值较大的词项作为最能代表该短文本的核心词项形成核心词项集;以信息论为基础,将核心词项作为划分依据计算平均划分相似度,选择平均划分相似度值最大包含该核心词项的短文本形成一类,用此策略反复迭代直到满足要求。最后,实验结果表明,本文提出的方法显著地提高了短文本聚类的性能。     

中文专利文献术语自动识别研究

中文专利文献中含有大量领域术语,对这些术语进行自动识别是信息抽取、文本挖掘等领域的重要任务。该文提出了基于专利文献标题的术语词性规则自动生成方法以及针对候选术语排序的TermRank算法。该方法首先从大量的中文专利文献标题中自动生成词性规则;然后利用生成的词性规则对中文专利文献正文部分进行规则匹配获得候选术语表;再利用提出的TermRank排序算法对候选术语表排序,最终得到术语列表。通过在9 725篇中文专利文献数据上实验,证实了该方法的有效性。
     

基于查询词扩展的文本检索算法研究

针对文本检索中所使用的查询词可能与文本词语不匹配而影响检索效果这一问题,提出了一种基于上下文的查询词扩展的方法,该方法根据查询词出现的上下文信息进行扩展词选择,同时考虑到查询扩展词与整个查询语句以及查询词的位置关系。实验结果表明,该方法大大提高了平均查准率。     

Context-dependent kernels for object classification

Kernels are functions designed in order to capture resemblance between data and they are used in a wide range of machine learning techniques, including support vector machines (SVMs). In their standard version, commonly used kernels such as the Gaussian one show reasonably good performance in many classification and recognition tasks in computer vision, bioinformatics, and text processing. In the particular task of object recognition, the main deficiency of standard kernels such as the convolution one resides in the lack in capturing the right geometric structure of objects while also being invariant. We focus in this paper on object recognition using a new type of kernel referred to as "context dependent.” Objects, seen as constellations of interest points, are matched by minimizing an energy function mixing 1) a fidelity term which measures the quality of feature matching, 2) a neighborhood criterion which captures the object geometry, and 3) a regularization term. We will show that the fixed point of this energy is a context-dependent kernel which is also positive definite. Experiments conducted on object recognition show that when plugging our kernel into SVMs, we clearly outperform SVMs with context-free kernels.     

维吾尔文论坛中基于术语选择和Rocchio分类器的文本过滤方法

针对维吾尔文网页论坛中的文本过滤问题,提出一种基于术语选择和Rocchio分类器的文本过滤方法。首先,将论坛文本进行预处理以删除无用词,并基于N-gram 统计模型进行词干(术语)提取;然后,提出一种均衡考虑相关性和冗余性的均衡型互信息术语选择方法(BMITS),对初始术语集合进行降维,获得精简术语集;最后,将文本特征术语作为输入,通过Rocchio分类器进行分类,以此过滤掉论坛中的不良文本。在相关数据集上的实验结果表明,提出的方法能够准确地识别出不良类型文本,具有有效性。     

基于概念格的Web文本聚类

Web文本聚类大多是基于空间向量文本表示模型的,它没有考虑特征词之间的语义关系,并且特征词的维数非常高,造成文本语义信息的损失和时间复杂度的增加。把文本作为对象,文本中的特征词作为对应的属性,形成了基于文本的形式背景,从中提取概念来表示文本并度量文本之间的相似度,从而降低了特征词的维数,减少了计算的复杂度,取得了良好的聚类结果。     

改进的增量词集频率主题词提取算法

为了解决基于增量词集频率的主题词提取算法不能提取合成词的问题,在原算法的基础上增加了文本预处理环节,即合成词识别。采用基于词性探测和词共现有向图算法识别文本中的合成词,并对分词结果进行修正。生成候选主题词集时,考察每个词的出现位置,根据不同的出现位置赋予不同的权重;然后累加获得同一个词的总权重,并按权重从高到低生成候选主题词集。提取主题词时逐个考察候选主题词集中的每一个候选主题词,计算其对主题词集权重的增量,若增量小于给定阈值,则主题词提取算法结束;否则将该候选主题词加入主题词集。实验结果表明,该算法取得了较好的效果,所获得的主题词能更贴切地反映文档的主题内容,主题词满意度比原算法提高了5个百分点。     

基于DC-Value的西班牙语文本词语提取方法

西班牙语(以下简称西语)是仅次于汉语的世界第二大母语语言, 是联合国6种官方语言之一. 西语复杂的词形变化和语法规则, 导致C-value等经典的词语提取方法的效果无法保证, 进而影响基于西语文本挖掘的效果.因此, 本文研究西语文本词语提取方法, 为西语文本的结构化建模提供完备的词库. 给定待分析的西班牙语文本, 该方法分3步提取得到词语集合: 文本预处理、候选词语提取和DC-value成词度计算. 其中, 前两步所得的候选词语集合可直接用作文本挖掘的词库; 第三步所得的候选词语成词度可辅助判断候选词语成词的可能性, 减轻人工判断的工作量. 实验结果表明, 本文方法自动提取的西文词语集合的准确率达到80％, 且召回率远高于经典方法, 能够为西语文本挖掘提供有效的词库.     

开放集文字识别技术

开放环境下的模式识别与文字识别应用中,新数据、新模式和新类别不断涌现,要求算法具备应对新类别模式的能力。针对这一问题,研究者们开始聚焦开放集文字识别（open-set text recognition,OSTR）任务。该任务要求,算法在测试（推断）阶段,既能识别训练集见过的文字类别,还能够识别、拒识或发现训练集未见过的新文字。开放集文字识别逐步成为文字识别领域的研究热点之一。本文首先对开放集模式识别技术进行简要总结,然后重点介绍开放集文字识别的研究背景、任务定义、基本概念、研究重点和技术难点。同时,针对开放集文字识别三大问题（未知样本发现、新类别识别和上下文信息偏差）,从方法的模型结构、特点优势和应用场景的角度对相关工作进行了综述。最后,对开放集文字识别技术的发展趋势和研究方向进行了分析展望。     

The combination of term relations analysis and weighted frequent itemset model for multidocument summarization

Nowadays, it is necessary that users have access to information in a concise form without losing any critical information. Document summarization is an automatic process of generating a short form from a document. In itemset-based document summarization, the weights of all terms are considered the same. In this paper, a new approach is proposed for multidocument summarization based on weighted patterns and term association measures. In the present study, the weights of the terms are not equal in the context and are computed based on weighted frequent itemset mining. Indeed, the proposed method enriches frequent itemset mining by weighting the terms in the corpus. In addition, the relationships among the terms in the corpus have been considered using term association measures. Also, the statistical features such as sentence length and sentence position have been modified and matched to generate a summary based on the greedy method. Based on the results of the DUC 2002 and DUC 2004 datasets obtained by the ROUGE toolkit, the proposed approach can outperform the state-of-the-art approaches significantly.     

Automatic recognition of multi-word terms:. the C-value/NC-value method

Technical terms (henceforth called terms ), are important elements for digital libraries. In this paper we present a domain-independent method for the automatic extraction of multi-word terms, from machine-readable special language corpora. The method, (C-value/NC-value ), combines linguistic and statistical information. The first part, C-value, enhances the common statistical measure of frequency of occurrence for term extraction, making it sensitive to a particular type of multi-word terms, the nested terms. The second part, NC-value, gives: 1) a method for the extraction of term context words (words that tend to appear with terms); 2) the incorporation of information from term context words to the extraction of terms. Received: 17 December 1998 / Revised: 19 May 1999     

基于快速DGMM的随机提示文本的话者确认系统

研究了随机提示文本的话者确认技术中的几个关键技术,包括确认算法的训练和识别速度、话者确认文本和说话方式的选择,测试文本长度的选择、阈值的设定及话者语音的中长期变异的自适应处 提高训练和识别速度,该文提出了快速动态高斯混合话者模型,讨论了音素对话者确认系统的影响及测试文本长度对话者确认系统性能的影响。提出话者语音假性的中长期变异性的自适应增量学习的方法,同时文中详细地分析了一次和多次测试时话者的弃真     

基于网络资源与用户行为信息的领域术语提取

领域术语是反映领域特征的词语.领域术语自动抽取是自然语言处理中的一项重要任务,可以应用在领域本体抽取、专业搜索、文本分类、类语言建模等诸多研究领域,利用互联网上大规模的特定领域语料来构建领域词典成为一项既有挑战性又有实际价值的工作.当前,领域术语提取工作所利用的网络语料主要是网页对应的正文,但是由于网页正文信息抽取所面临的难题会影响领域术语抽取的效果,那么利用网页的锚文本和查询文本替代网页正文进行领域术语抽取,则可以避免网页正文信息抽取所面临的难题.针对锚文本和查询文本所存在的文本长度过短、语义信息不足等缺点,提出一种适用于各种类型网络数据及网络用户行为数据的领域数据提取方法,并使用该方法基于提取到的网页正文数据、网页锚文本数据、用户查询信息数据、用户浏览信息数据等开展了领域术语提取工作,重点考察不同类型网络资源和用户行为信息对领域术语提取工作的效果差异.在海量规模真实网络数据上的实验结果表明,基于用户查询信息和用户浏览过的锚文本信息比基于网页正文提取技术得到的正文取得了更好的领域术语提取效果.     

基于WordNet概念向量空间模型的文本分类

文章提出了一种文本特征提取方法,以WordNet语言本体库为基础,以同义词集合概念代替词条,同时考虑同义词集合间的上下位关系,建立文本的概念向量空间模型作为文本特征向量,使得在训练过程中能够提取出代表类别的高层次信息。实验结果表明,当训练文本集合很小时,方法能够较大地提高文本的分类准确率。     

基于BERT的手术名称标准化重排序算法

临床术语标准化是医学文本信息抽取中不可或缺的一项任务.临床上对于同一种诊断、手术、药品、检查、化验、症状等,往往会有多种不同的写法,术语标准化(归一)要解决的问题就是为临床上各种不同的说法找到对应的标准名称.在检索技术生成候选答案的基础上,该文提出了基于BERT(bidirectional encoder repres...     

A Novel Context-based Technique for Web Information Retrieval

In this paper we present context matching, a novel context-based technique for the ad-hoc retrieval of web documents. The aim of the technique is to dynamically generate a measure of document term significance during retrieval that can be used as a substitute or co-contributor of the term frequency measure. Unlike term frequency, which relies on a term occurring multiple times in a document to be considered significant, context matching is based on the notion that if a term in a given document occurs in that document in the context of the query, then that term is deemed to be significant. Context matching has the ability to potentially determine a term to be significant even if it occurs only once in a document. Vice versa, it also has the ability to determine a term to be insignificant, even if occurs frequently within a document. We show how expanded terms generated by a typical query expansion technique can be used effectively as query context for context matching. The technique is ideally suited to the nature of web information retrieval and we show how context matching significantly improves retrieval accuracy through experimental results on TREC web benchmark data.     

Conditional Term Graph Rewriting with Indirect Sharing

For reasons of efficiency, term rewriting is usually implemented by term graph rewriting. In term rewriting, expressions are represented as terms, whereas in term graph rewriting these are represented as directed graphs. Unlike terms, graphs allow a sharing of common subexpressions. In previous work, we have shown that conditional term graph rewriting is a sound and complete implementation for a certain class of CTRSs with strict equality, provided that a minimal structure sharing scheme is used. In this paper, we will show that this is also true for two different extensions of normal CTRSs. In contrast to the previous work, however, a non-minimal structure sharing scheme can be used. That is, the amount of sharing is increased.