6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268)最新文献_第3页

Problems related to subsequences and supersequences 与子序列和超序列有关的问题

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796596

Zdenek Tronícek

引用次数: 8

A fast and space-economical algorithm for calculating minimum redundancy prefix codes 一种快速且节省空间的最小冗余前缀码计算算法

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796587

R. Milidiú, A. Pessoa, E. Laber

{"title":"A fast and space-economical algorithm for calculating minimum redundancy prefix codes","authors":"R. Milidiú, A. Pessoa, E. Laber","doi":"10.1109/SPIRE.1999.796587","DOIUrl":"https://doi.org/10.1109/SPIRE.1999.796587","url":null,"abstract":"The minimum redundancy prefix code problem is to determine, for a given list W=[w/sub 1/,...,w/sub n/] of n positive symbol weights, a list L=[l/sub 1/,...,l/sub n/] of n corresponding integer codeword lengths such that /spl Sigma//sub i=1//sup n/2/sup -li//spl les/1 and /spl Sigma//sub i=1//sup n/w/sub i/l/sub i/ is minimized. With the optimal list of codeword lengths, an optimal canonical code can be easily obtained. If W is already sorted, then this optimal code can also be represented by the list M=[m/sub 1/,...,m/sub H/], where m/sub l/, for l=1,...,H, denotes the number of codewords with length l and H is the length of the longest codeword. Fortunately, H is proved to be O(min{log(1/p/sub 1/),n}, where p/sub 1/ is the smallest symbol probability, given by w/sub 1///spl Sigma//sub i=1//sup n/w/sub i/. The E-LazyHuff algorithm uses a lazy approach to calculate optimal codes in O(nlog(n/H)) time, requiring only O(H) additional space. In addition, the input weights are not destroyed during the code calculation. We propose a new technique, which we call homogenization, that can be used to improve the time efficiency of algorithms for constructing optimal prefix codes. Next, we introduce the Best LazyHuff algorithm (B-LazyHuff) as an application of this technique. B-LazyHuff is an O(n)-time variation of the E-LazyHuff algorithm. It also requires O(H) additional space and does not destroy the input data.","PeriodicalId":131279,"journal":{"name":"6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116361348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Contextual array splicing systems 上下文数组拼接系统

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796592

R. Rama, S. Krishna

引用次数: 5

Actor-oriented management of cooperative work 面向参与者的协同工作管理

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796616

F. Bodendorf, R. Grebner

引用次数: 1

Design patterns for collaborative systems 协作系统的设计模式

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796604

Luis A. Guerrero, David A. Fuller

引用次数: 14

Approximate retrieval from multimedia databases using relevance feedback 利用相关反馈从多媒体数据库中近似检索

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796598

A. Lelescu, O. Wolfson, Bo Xu

引用次数: 10

The ADT proximity and text proximity problems ADT接近和文本接近问题

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796574

Ricardo Baeza-Yates, W. Cunto

引用次数: 6

An associative semantic model for text processing 文本处理的关联语义模型

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796575

Alejandro Bassi

引用次数: 1

Flexible communication support for CSCW applications 灵活的通信支持CSCW应用程序

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796612

Hugo M. Miranda, L. Rodrigues

引用次数: 19

Practical constructions of L-restricted alphabetic prefix codes l限制字母前缀码的实用构造

6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268) Pub Date : 1999-09-21 DOI: 10.1109/SPIRE.1999.796585

E. Laber, R. Milidiú, A. Pessoa

{"title":"Practical constructions of L-restricted alphabetic prefix codes","authors":"E. Laber, R. Milidiú, A. Pessoa","doi":"10.1109/SPIRE.1999.796585","DOIUrl":"https://doi.org/10.1109/SPIRE.1999.796585","url":null,"abstract":"Information retrieval systems use various search techniques such as B-trees, inverted files and suffix arrays to provide quick response. Many of these techniques rely on string comparison operations. If a record field is coded using Huffman codes (D.A. Huffman, 1952) in order to save storage space, the field must be decoded before performing any comparison. On the other hand, if the field is alphabetically coded, then the comparison can be directly applied to the sequence of codewords, which is faster. This approach also saves storage space, in comparison with the case where no data compression is applied. Experiments with alphabetically coded texts indexed with suffix arrays were reported by E.S. Moura et al. (1997). We consider the construction of L-restricted ABPC (alphabetic binary prefix code) which satisfies l/sub i//spl les/L for i=1,...,n. Optimal L-restricted ABPC can be constructed in O(nLlogn) time, using O(nL) space (L.L Larmore and T.M. Przytycka, 1994). Nevertheless, due to its space requirements, this method turns out to be prohibitive for larger values of n. We suggest a simple approach to construct suboptimal L-restricted ABPC. Our approach is divided into three phases. In the first phase, we verify if an optimal ABPC is also an optimal L-restricted ABPC. In the second one, we obtain a L-restricted prefix code (not necessarily alphabetical) and in the third phase we turn this code into an alphabetical one. We denote this approach by 3-phase algorithm . The codes generated through this algorithm are called 3-phase codes. We analyze the time and space complexities and compare the average length of the 3-phase code against the Shannon Entropy. We also compare the average length of the Huffman code against the average length of an optimal L-restricted ABPC.","PeriodicalId":131279,"journal":{"name":"6th International Symposium on String Processing and Information Retrieval. 5th International Workshop on Groupware (Cat. No.PR00268)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129745362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3