A. Bookstein and S. T. Klein. Compression of correlated bit-vectors. Information Systems, 16(4):110--118, 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....minimum spanning trees and shallow light spanning trees. The search for a BDMST finds applications in such areas as telecommunications network and linear lightwave network design [2] distributed system design when considering mutual exclusion [17] and bit compression for information retrieval [3]. A special case occurs when D = 4 and a root vertex is specified. This is called the 2 hop problem [5] The BDMST problem is NP hard for 4 1 [7, p. 206] and no exact algorithm is known that identifies optimum solutions on large problem instances. Kortsarz and Peleg [12] have shown that, ....

A. Bookstein and S. T. Klein. Compression of correlated bit-vectors. Information Systems, 16(4):110--118, 1996.

....tree. Therefore, a small diameter is essential for the efficiency of the algorithm. Minimizing edge weights reduces the cost of the network. A DCMST is also useful in information retrieval, where large data structures called bitmaps are used in compressing large files. Bookstein and Klein [7] proposed using a spanning tree to cluster bitmap vectors and compress them, where smaller spanning tree weight results in less storage space. However, to recover a given bitmap vector, all nodes in a path in the spanning tree must be decompressed. Therefore, the compression spanning tree should ....

Bookstein, A., Klein, S.T., "Compression of correlated bit-vectors," Information Systems, 16(4) (1991), pp. 387-400.

....distance is measured by number of edges) Hereafter we refer to this problem as the Bounded Diameter Minimum Steiner Tree (BDST) problem. This problem arises in various contexts in communication network design. It has also been given some applications in the area of information retrieval in [BK90, BK91] There, shallow trees are used to efficiently compress a collection An extended abstract of this work was presented at the Eighth ACM SIAM Symp. on Discrete Algorithms, Jan. 1997, under the title Approximating shallow light trees . y Department of Computer Science, The Open University of ....

A. Bookstein and S.T. Klein. Compression of correlated bit-vectors. Information Systems, 16:387--400, 1991.

....that they have little or no effect on run time retrieval performance. 2 Document Collections We have tested our bitmap compression techniques on three collections of documents. Table 1 shows the sizes of these collections. The collection Manuals was a collection of Unix manual pages ( usr man man[1 8] on a Sun SPARCstation) including embedded formatting commands. Collection GNUbib [18] stores 64,000 citations to journal articles, technical reports, conference papers, and books, all stored in refer format [13, 20] Each citation was taken to be a document for indexing purposes. The third ....

....code, and with a batched variant, where the code was selected according to blog p w c. Again there is a small, but definite, improvement in the compression performance. 8 Comparison with Other Methods There has been a great deal of previous work on bitmap compression, and many methods proposed [1, 2, 3, 4, 5, 8, 12, 17, 19, 21]. It is interesting to compare the compression possible with the parameterised models with those previous methods. Compression Manuals GNUbib Comact Huffman (global) 49.8 32.3 25.9 Global model 0.5 0.7 0.1 Total 50.3 33.0 26.0 Huffman (batched) 44.1 30.2 24.6 dlog Ne models 1.6 0.9 0.2 ....

A. Bookstein and S.T. Klein. Compression of correlated bit-vectors. Information Systems, 16(4):387--400, 1991.

....(Perl et al. 1978) can be employed providing a more rapid means for testing, union and intersection operations than the other list encoding methods described above. 3.5. PARTITIONS OF BIT VECTORS Another method of storing the sets is to partition each one into blocks of approximately equal length (Bookstein Klein, 1991). If there are b blocks, a vector of length b is built whose ith bit is 1 if the ith partition in the original set contains any 1bits. This vector is then followed by bit vectors for only those partitions that are non empty. This method compresses the original set if it contains few 1 bits. 3.6. ....

....partition in the original set contains any 1bits. This vector is then followed by bit vectors for only those partitions that are non empty. This method compresses the original set if it contains few 1 bits. 3.6. PARTITIONS OF LISTS OF INDEXES Instead of using a bit vector to store the partition, Bookstein Klein (1991) suggested storing a list of offsets for each 1 bit. This reduces the storage required at the cost of extra time spent during membership and intersection operations. 3.7. BITMAP TREES The partitioning technique can be extended by repeating it to create a tree of bit vectors, with whole subtrees ....

Bookstein, A. and Klein, S.T. (1991) Compression of correlated bit-vectors. Information Systems 16(4): 387-- 400.

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A. Bookstein and S. Klein. Compression of correlated bit-vectors. Information Systems, 16(4), 1991.

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