首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   14篇
  国内免费   1篇
  完全免费   11篇
  自动化技术   26篇
  2018年   2篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   2篇
  2012年   4篇
  2011年   1篇
  2010年   3篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   1篇
  2004年   1篇
  2003年   1篇
  2001年   1篇
排序方式: 共有26条查询结果,搜索用时 31 毫秒
1.
基于扩展路径表达式的XML查询   总被引:4,自引:0,他引:4  
XML查询问题是当前计算机界研究的热点问题之一,国内外学者提出了众多的模型与算法.其中,日本学者Makoto Murata等提出采用扩展路径表达式来表达查询,并利用hedge自动机和字符串自动机进行XML的查询计算.这种方法与采用路径表达式控制的XML查询相比,克服了后者不能充分利用XML文档有序性的缺点.另外,扩展路径表达式具有较强的表达能力,可以表达任何MSO(一元二阶逻辑)查询.因此,扩展路径表达式已作为XML查询问题研究的主要理论框架之一,但是扩展路径表达式的编写比较困难,表达式也比较复杂,导致算法时间复杂度的提高.在扩展路径表达式中引入通配符,使得扩展路径表达式更加简单灵活;同时在查询的计算过程中提出并应用带截止集的自动机提高计算的时间效率.  相似文献
2.
Efficient string matching with wildcards and length constraints   总被引:2,自引:2,他引:0  
This paper defines a challenging problem of pattern matching between a pattern P and a text T, with wildcards and length constraints, and designs an efficient algorithm to return each pattern occurrence in an online manner. In this pattern matching problem, the user can specify the constraints on the number of wildcards between each two consecutive letters of P and the constraints on the length of each matching substring in T. We design a complete algorithm, SAIL that returns each matching substring of P in T as soon as it appears in T in an O(n+klmg) time with an O(lm) space overhead, where n is the length of T, k is the frequency of P's last letter occurring in T, l is the user-specified maximum length for each matching substring, m is the length of P, and g is the maximum difference between the user-specified maximum and minimum numbers of wildcards allowed between two consecutive letters in P.SAIL stands for string matching with wildcards and length constraints. Gong Chen received the B.Eng. degree from the Beijing University of Technology, China, and the M.Sc. degree from the University of Vermont, USA, both in computer science. He is currently a graduate student in the Department of Statistics at the University of California, Los Angeles, USA. His research interests include data mining, statistical learning, machine learning, algorithm analysis and design, and database management. Xindong Wu is a professor and the chair of the Department of Computer Science at the University of Vermont. He holds a Ph.D. in Artificial Intelligence from the University of Edinburgh, Britain. His research interests include data mining, knowledge-based systems, and Web information exploration. He has published extensively in these areas in various journals and conferences, including IEEE TKDE, TPAMI, ACM TOIS, IJCAI, AAAI, ICML, KDD, ICDM and WWW, as well as 12 books and conference proceedings. Dr. Wu is the Editor-in-Chief of the IEEE Transactions on Knowledge and Data Engineering (by the IEEE Computer Society), the founder and current Steering Committee Chair of the IEEE International Conference on Data Mining (ICDM),an Honorary Editor-in-Chief of Knowledge and Information Systems (by Springer), and a Series Editor of the Springer Book Series on Advanced Information and Knowledge Processing (AI&KP). He is the 2004 ACM SIGKDD Service Award winner. Xingquan Zhu received his Ph.D degree in Computer Science from Fudan University, Shanghai, China, in 2001. He spent 4 months with Microsoft Research Asia, Beijing, China, where he was working on content-based image retrieval with relevance feedback. From 2001 to 2002, he was a postdoctoral associate in the Department of Computer Science at Purdue University, West Lafayette, IN. He is currently a research assistant professor in the Department of Computer Science, the University of Vermont, Burlington, VT. His research interests include data mining, machine learning, data quality, multimedia computing, and information retrieval. Since 2000, Dr. Zhu has published extensively, including over 50 refereed papers in various journals and conference proceedings. Abdullah N. Arslan got his Ph.D. degree in Computer Science in 2002 from the University of California at Santa Barbara. Upon his graduation he joined the Department of Computer Science at the University of Vermont as an assistant professor. He has been with the computer science faculty there since then. Dr. Arslan's main research interests are on algorithms on strings, computational biology and bioinformatics. Dr. Arslan earned his Master's degree in Computer Science in 1996 from the University of North Texas, Denton, Texas and his Bachelor's degree in Computer Engineering in 1990 from the Middle East Technical University, Ankara, Turkey. He worked as a programmer for the Central Bank of Turkey between 1991 and 1994. Yu He received her B.E. degree in Information Engineering from Zhejiang University, China, in 2001. She is currently a graduate student in the Department of Computer Science at the University of Vermont. Her research interests include data mining, bioinformatics and pattern recognition.  相似文献
3.
支持带有通配符的字符串匹配算法   总被引:1,自引:0,他引:1       下载免费PDF全文
研究了查询字符串中含有通配符"*"以及"?"两种情况下的字符串匹配问题,其中,"*"代表任意长度的字符串,"?"代表字母表中任意一个字符。由于gram索引结构在空间大小以及查询效率上的优势,将gram索引结构用于带通配符的字符串匹配问题。通过将带有通配符的查询字符串分解为若干不含通配符的查询片段,成功地将带有通配符的复杂查询问题转化为不含通配符的简单精确子串匹配问题。同时在片段查询过程中运用长度过滤、位置过滤以及计数过滤等方法来提高查询速度。  相似文献
4.
Matching with don't-cares and a small number of mismatches   总被引:1,自引:0,他引:1  
In matching with don't-cares and k mismatches we are given a pattern of length m and a text of length n, both of which may contain don't-cares (a symbol that matches all symbols), and the goal is to find all locations in the text that match the pattern with at most k mismatches, where k is a parameter. We present new algorithms that solve this problem using a combination of convolutions and a dynamic programming procedure. We give randomized and deterministic solutions that run in time O(nk2logm) and O(nk3logm), respectively, and are faster than the most efficient extant methods for small values of k. Our deterministic algorithm is the first to obtain an O(polylog(k)⋅nlogm) running time.  相似文献
5.
基于后缀树的带有通配符的模式匹配研究   总被引:1,自引:1,他引:0  
由于在生物序列分析、文本索引、网络入侵检测等领域的应用需求,带有通配符的模式匹配问题一直是研究 的热点。针对已有的研究工作中通配符和长度约束具有较强的局限性问题,研究带有灵活通配符的模式匹配问题,其 中通配符可以在模式的任意两子串间出现且可以指定灵活的长度约束。采用非线性数据结构—后缀树,设计了求 解模式所有解的完备算法PAS"I'。预处理阶段采用在线增量式算法构建具有文本先验知识的后缀树,搜索阶段结合 动态规划的思想,逐个匹配模式中字符,最终得到完备解。在基因序列上的实验表明,PAST比其他算法具有更好的 时间性能。  相似文献
6.
本文阐述了Java中泛型的概念和特点,介绍了简单泛型创建和使用,探讨了泛型应用中存在的陷井。泛型最重要的特点是类型安全,泛型还可以消除类型转换等。泛型的创建和使用比较简单,但在使用中存在一定的陷阱,需要引起程序员的注意。  相似文献
7.
We present a simple and fast deterministic solution to the string matching with don't cares problem. The task is to determine all positions in a text where a pattern occurs, allowing both pattern and text to contain single character wildcards. Our algorithm takes O(nlogm) time for a text of length n and a pattern of length m and in our view the algorithm is conceptually simpler than previous approaches.  相似文献
8.
王燚 《计算机应用》2004,24(10):121-124
提出了一种新的相似字符串查询的方法。其目的在于提高基于相似字符串匹配的查询在大规模字符串数据库中的查询效率,并且提供带通配符的字符串查询方式。该方法使用Trie数据结构组织数据库中的数据,使用基于编辑距离的相似字符串匹配方法,在Trie数据结构中进行高效的匹配和查询,得到K相似度下的候选词集。实验证明,本方法在K≤2时具有相当高的查询效率。  相似文献
9.
Variability in handwriting styles suggests that many letter recognition engines cannot correctly identify some handwritten letters of poor quality at reasonable computational cost. Methods that are capable of searching the resulting sparse graph of letter candidates are therefore required. The method presented here employs ‘wildcards’ to represent missing letter candidates. Multiple experts are used to represent different aspects of handwriting. Each expert evaluates closeness of match and indicates its confidence. Explanation experts determine the degree to which the word alternative under consideration explains extraneous letter candidates. Schemata for normalisation and combination of scores are investigated and their performance compared. Hill climbing yields near-optimal combination weights that outperform comparable methods on identical dynamic handwriting data.  相似文献
10.
研究了带有灵活通配符和长度约束的近似模式匹配问题(approximate pattern matching with wildcards and length constraint,APMWL);为避免文本字符重复使用造成解的指数级增长,引入了一次性使用原则one_off条件,提出了一种后向构造编辑距离矩阵的BAPM(backward approximate pattern matching)算法。该算法在one_off条件、灵活通配符和长度约束条件的基础上,可同时处理插入、替换和删除三种编辑操作。与同类算法Sail_Approx进行实验对比,结果表明BAPM算法获取解的平均增长率可达18.99%,具备良好的解优势。  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号