A passage retrieval strategy for web-based question answering （QA） systems is proposed in our QA system. It firstly analyzes the question based on semantic patterns to obtain its syntactic and semantic information a...A passage retrieval strategy for web-based question answering （QA） systems is proposed in our QA system. It firstly analyzes the question based on semantic patterns to obtain its syntactic and semantic information and then form initial queries. The queries are used to retrieve documents from the World Wide Web （WWW） using the Google search engine. The queries are then rewritten to form queries for passage retrieval in order to improve the precision. The relations between keywords in the question are employed in our query rewrite method. The experimental result on the question set of the TREC-2003 passage task shows that our system performs well for factoid questions.展开更多
Pattern recognition is a task of searching particular patterns or features in the given input. The data mining, computer networks, genetic engineering, chemical structure analysis, web services etc. are few rapidly gr...Pattern recognition is a task of searching particular patterns or features in the given input. The data mining, computer networks, genetic engineering, chemical structure analysis, web services etc. are few rapidly growing applications where pattern recognition has been used. Graphs are very powerful model applied in various areas of computer science and engineering. This paper proposes a graph based algorithm for performing the graphical symbol recognition. In the proposed approach, a graph based filtering prior to the matching is performed which significantly reduces the computational complexity. The proposed algorithm is evaluated using a large number of input drawings and the simulation results show that the proposed algorithm outperforms the existing algorithms.展开更多
高效的在线字符串模式匹配算法对云数据库检索至关重要,然而搜索内容的泄露会威胁用户隐私。现有的字符串模式匹配算法没有考虑用户搜索内容的保护,可搜索加密方案虽然可以保护用户的搜索内容,但存在索引构建代价大、检索效率低等问题...高效的在线字符串模式匹配算法对云数据库检索至关重要,然而搜索内容的泄露会威胁用户隐私。现有的字符串模式匹配算法没有考虑用户搜索内容的保护,可搜索加密方案虽然可以保护用户的搜索内容,但存在索引构建代价大、检索效率低等问题。因此,提出了两种保护用户搜索内容的模式匹配算法:基于分布式点函数的模式匹配(pattern matching based on distributed point function,PMDPF)算法和基于分布式点函数的跳跃式模式匹配(jumping pattern matching based on distributed point function,JPMDPF)算法。PMDPF算法利用指纹函数以及分布式点函数构造模式串真值表,并分发给两台独立的服务器,把搜索中字符对比操作转换为查表操作,从而保护搜索内容。为了提升搜索效率,提出了JPMDPF算法。通过字符跳转,JPMDPF算法以泄露更多信息为代价,其搜索效率比PMDPF算法平均提高了约m倍,其中m为搜索内容长度,同时显著降低了因指纹函数碰撞而导致的误判的概率。实验结果表明,PMDPF算法的搜索效率比基于指纹函数的经典算法提高约5%,并优于现有的可搜索加密方案,PMDPF算法的搜索耗时在搜索内容长度为4时是JPMDPF算法的4.2倍。展开更多
基金Supported by the National Basic Research Program of China (2003CB317002)the Grant from City University of Hong Kong (7002137)
文摘A passage retrieval strategy for web-based question answering （QA） systems is proposed in our QA system. It firstly analyzes the question based on semantic patterns to obtain its syntactic and semantic information and then form initial queries. The queries are used to retrieve documents from the World Wide Web （WWW） using the Google search engine. The queries are then rewritten to form queries for passage retrieval in order to improve the precision. The relations between keywords in the question are employed in our query rewrite method. The experimental result on the question set of the TREC-2003 passage task shows that our system performs well for factoid questions.
文摘Pattern recognition is a task of searching particular patterns or features in the given input. The data mining, computer networks, genetic engineering, chemical structure analysis, web services etc. are few rapidly growing applications where pattern recognition has been used. Graphs are very powerful model applied in various areas of computer science and engineering. This paper proposes a graph based algorithm for performing the graphical symbol recognition. In the proposed approach, a graph based filtering prior to the matching is performed which significantly reduces the computational complexity. The proposed algorithm is evaluated using a large number of input drawings and the simulation results show that the proposed algorithm outperforms the existing algorithms.
文摘高效的在线字符串模式匹配算法对云数据库检索至关重要,然而搜索内容的泄露会威胁用户隐私。现有的字符串模式匹配算法没有考虑用户搜索内容的保护,可搜索加密方案虽然可以保护用户的搜索内容,但存在索引构建代价大、检索效率低等问题。因此,提出了两种保护用户搜索内容的模式匹配算法:基于分布式点函数的模式匹配(pattern matching based on distributed point function,PMDPF)算法和基于分布式点函数的跳跃式模式匹配(jumping pattern matching based on distributed point function,JPMDPF)算法。PMDPF算法利用指纹函数以及分布式点函数构造模式串真值表,并分发给两台独立的服务器,把搜索中字符对比操作转换为查表操作,从而保护搜索内容。为了提升搜索效率,提出了JPMDPF算法。通过字符跳转,JPMDPF算法以泄露更多信息为代价,其搜索效率比PMDPF算法平均提高了约m倍,其中m为搜索内容长度,同时显著降低了因指纹函数碰撞而导致的误判的概率。实验结果表明,PMDPF算法的搜索效率比基于指纹函数的经典算法提高约5%,并优于现有的可搜索加密方案,PMDPF算法的搜索耗时在搜索内容长度为4时是JPMDPF算法的4.2倍。
