| 倒排文档压缩技巧d-gaps的改进——文档标识号重置法 |
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| 引用本文： | 张爱红.倒排文档压缩技巧d-gaps的改进——文档标识号重置法[J].现代图书情报技术,2004,20(8):61-65. |
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| 作者姓名： | 张爱红 |
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| 作者单位： | 四川大学信息管理系,成都,610064 |
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| 摘 要： | 倒排文档是信息检索系统中最普遍使用的索引机制,而索引文件的压缩能大大提高检索速度和节约磁盘空间。倒排文件压缩的传统做法是文档(标识号)间距法（d-gaps）。然而，剧烈变化的间距值并不能被著名的前缀自由代码有效编码压缩。为了使间距值得到有效的压缩，本文设计了一个文档标识号重置法。模拟试验表明能更有效压缩d-gaps倒排文档。
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| 关 键 词： | 倒排文档 文档(标识号)间距法 文档标识号重置法 旅行商问题 贪心算法 最大生成树 |
| 收稿时间： | 2004-03-08 |
| 修稿时间： | 2004年3月8日 |
Improve the d-gaps Technique for Inverted File Compression: Document Identifier Reassignment |
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| Zhang Aihong.Improve the d-gaps Technique for Inverted File Compression: Document Identifier Reassignment[J].New Technology of Library and Information Service,2004,20(8):61-65. |
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| Authors: | Zhang Aihong |
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| Institution: | (Department of Information Management, Sichuan University, Chengdu 610064,China) |
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| Abstract: | The inverted file is the most popular indexing mechanism in an information retrieval system. Compressing an inverted file can greatly improve document search rate and save disk space. Traditionally, the d-gaps technique is used in the inverted file compression by replacing document identifiers with usually much smaller gap values. However, fluctuating gap values cannot be efficiently compressed by some well-known prefix-free codes. In this paper, a document identifier reassignment algorithm is proposed to reduce the gap values. Simulation results show that the average gap values of the inverted files can be reduced effectively. |
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| Keywords: | Inverted file d-gaps Document identifier reassignment TSP (Traveling Salesman Problem) The greedy algorithm MaxST |
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