共查询到19条相似文献，搜索用时 125 毫秒
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本文首先证明了布尔减、布尔除与非运算构成完备集,并根据布尔减、布尔除与非运算的运算规则和性质,从与或非代数系统中的最小项、最大项展开式出发,推导了任意逻辑函数在减除非代数系统中的标准DOS(减之除)和标准SOD(除之减)展开式。最后举例说明了二个代数系统中展开式之间的转换。本文的工作对进一步完善布尔代数的四则运算理论具有一定的意义。 相似文献
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讨论了逻辑函数最大项展开式和COD展开式的矩阵转换方法,分析了K图和gj图之间转换的图形方法.在此基础上提出了最大项展开系数和除一符合展开系数转换的表格方法.与图形方法相比,表格方法具有不受变量数目约束,易于计算机的实现等优点.具有较好的实用性. 相似文献
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一、引言逻辑函数具有表格式(真值表)、代数式及图形(K图)等三种表示形式,其中的K图表示由于具有相邻格可以合并的特点,因此,它在二值或多值逻辑函数的简化中提供了直观与方便的综合程序。然而,逻辑函数的图形表示受到变量数的限制,这是由于随变量数的增加,K图的规模按基数的幂次规律迅速增加。在二值逻辑中,为了扩大K图的适用范围已引入了降维K图的方法,它乃是把一个n变量的函数用一个m维(m相似文献
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在高等数学中,幂级数讨论的主要问题有两类：求其在某收敛域上的和函数;求函数的幂级数展开式。本文通过实例,介绍了等比级数的收敛公式在这两方面的具体应用。 相似文献
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论文给出了关于0-1编码谱系数与最小项展开系数之间关系的两个定理,在此基础上提出了0-1编码谱系数与最小项展开系数之间转换的代数方法.实例展示了用代数方法实现相互转换的过程.与传统的图形转换方法相比,该方法具有不受变量数限制的优点. 相似文献
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基于图形方法的最小项展开系数与Reed-Muller展开系数之间的转换 总被引：1，自引：0，他引：1
通过研究布尔函数二类规范展开形式之间的关系,在综述现有图形转换方法的基础上,对原有的图形方法作了补充,从而进一步揭示了最小项展开系数与Reed-Muller展开系数之间的内在联系,形成了较为完整的图形转换方法. 相似文献
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《Information processing & management》2022,59(5):103026
Pseudo-relevance feedback (PRF) is a classical technique to improve search engine retrieval effectiveness, by closing the vocabulary gap between users’ query formulations and the relevant documents. While PRF is typically applied on the same target corpus as the final retrieval, in the past, external expansion techniques have sometimes been applied to obtain a high-quality pseudo-relevant feedback set using the external corpus. However, such external expansion approaches have only been studied for sparse (BoW) retrieval methods, and its effectiveness for recent dense retrieval methods remains under-investigated. Indeed, dense retrieval approaches such as ANCE and ColBERT, which conduct similarity search based on encoded contextualised query and document embeddings, are of increasing importance. Moreover, pseudo-relevance feedback mechanisms have been proposed to further enhance dense retrieval effectiveness. In particular, in this work, we examine the application of dense external expansion to improve zero-shot retrieval effectiveness, i.e. evaluation on corpora without further training. Zero-shot retrieval experiments with six datasets, including two TREC datasets and four BEIR datasets, when applying the MSMARCO passage collection as external corpus, indicate that obtaining external feedback documents using ColBERT can significantly improve NDCG@10 for the sparse retrieval (by upto 28%) and the dense retrieval (by upto 12%). In addition, using ANCE on the external corpus brings upto 30% NDCG@10 improvements for the sparse retrieval and upto 29% for the dense retrieval. 相似文献
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We present new methods of query expansion using terms that form lexical cohesive links between the contexts of distinct query terms in documents (i.e., words surrounding the query terms in text). The link-forming terms (link-terms) and short snippets of text surrounding them are evaluated in both interactive and automatic query expansion (QE). We explore the effectiveness of snippets in providing context in interactive query expansion, compare query expansion from snippets vs. whole documents, and query expansion following snippet selection vs. full document relevance judgements. The evaluation, conducted on the HARD track data of TREC 2005, suggests that there are considerable advantages in using link-terms and their surrounding short text snippets in QE compared to terms selected from full-texts of documents. 相似文献
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广州市城市扩张和经济发展之间的关系 总被引：1，自引：1，他引：0
本文基于广州市1987年-2010年的建成区面积和第二、三产业GDP的统计数据,应用协整分析、库兹涅茨曲线和“脱钩”理论对建成区面积扩张和经济发展之间的关系进行实证研究.结果表明两者之间存在长期协整关系,并得到两者之间的协整方程,通过Granger因果检验,发现两者之间不存在Granger因果关系.通过误差修正模型发现修正系数为负,符合误差修正机制.通过对建成区面积和第二、三产业GDP之关系的库兹涅茨曲线研究,结果表明两者的坐标曲线呈倒“U”型.进一步对建成区面积扩张和第二、三产业GDP进行总量脱钩研究,探究不同发展阶段城市扩张和经济发展的关系. 相似文献
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检测逻辑函数对称性的新方法 总被引：6，自引：0，他引：6
本文论述了逻辑函数的Ｒｅｅｄ－Ｍｕｌｌｅｒ展开及ｂ＿ｊ系数图，在此基础上提出了直接检测基于Ｒｅｅｄ－Ｍｕｌｌｅｒ展开的逻辑函数的对称性的新方法。 相似文献
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Analyzing the impact of knowledge management on CRM success: The mediating effects of organizational factors 总被引：1，自引：0，他引：1
Aurora Garrido-MorenoAuthor Vitae Antonio Padilla-MeléndezAuthor Vitae 《International Journal of Information Management》2011,31(5):437-444
Customer relationship management (CRM) and knowledge management (KM) have become key strategic tool for all companies, especially in the current competitive environment. Moreover, customer knowledge is an important issue for CRM implementation. Reviewing the literature, we found many studies that analyze the crucial role played by KM initiatives as determinants of the success of CRM. Moreover, we found also diverse studies that show high rates of failure when implementing that strategy, so there is still no integrated conceptual framework to guide companies to their successful implementation. In this paper, with data of 153 Spanish hotels, we examine the relationships between KM and CRM success using a structural equation model. The main contribution is that having knowledge management capabilities is not sufficient for the success of CRM, but there are other factors to consider. In particular, organizational factors indeed impact CRM success and they appear to be intermediaries of the impact of other factors (KM capabilities/technological/customer orientation factors) in the success of CRM (in financial and marketing terms). 相似文献