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ABSTRACT
This paper discusses an index-based subsequence matching that supports time warping in large sequence databases. Time warping enables finding sequences with similar patterns even when they are of different lengths. In our earlier work, we suggested an efficient method for whole matching under time warping. This method constructs a multi-dimensional index on a set of feature vectors, which are invariant to time warping, from data sequences. For filtering at feature space, it also applies a lower-bound function, which consistently underestimates the time warping distance as well as satisfies the triangular inequality.In this paper, we incorporate the prefix-querying approach based on sliding windows into the earlier approach. For indexing, we extract a feature vector from every subsequence inside a sliding window and construct a multi-dimensional index using a feature vector as indexing attributes. For query processing, we perform a series of index searches using the feature vectors of qualifying query prefixes. Our approach provides effective and scalable subsequence matching even with a large volume of a database. We also prove that our approach does not incur false dismissal. To verify the superiority of our method, we perform extensive experiments. The results reveal that our method achieves significant speedup with real-world S&P 500 stock data and with very large synthetic data. REFERENCES
Note: OCR errors may be found in this Reference List extracted from the full text article. ACM has opted to expose the complete List rather than only correct and linked references. 1 R. Agrawal, C. Faloutsos, and A. Swami. Efficient similarity search in sequence databases. In Proc. FODO, pages 69-84, 1993. 2 R. Agrawal, K. Lin, H. S. Sawhney, and K. Shim. Fast similarity search in the presence of noise, scaling, and translation in time-series databases. In Proc. VLDB, pages 490-501, 1995. 4 S. Berchtold, D. A. Keim, and H. Kriegel. The X-tree: An index structure for high-dimensional data. In Proc. VLDB, pages 28-39, 1996. 6 M. S. Chen, J. Han, and P. S. Yu. Data mining: An overview from database perspective. IEEE TKDE, 8(6):866-883, 1996. 8 G. Das, D. Gunopulos, and H. Mannila. Finding similar time series. In Proc. PKDD, pages 88-100, 1997. 10 D. Q. Goldin and P. C. Kanellakis. On similarity queries for time-series data: Constraint specification and implementation. In Proc. Constraint Programming, pages 137-153, 1995. 11 A. Guttman. R-tree: A dynamic index structure for spatial searching. In Proc. ACM SIGMOD, pages 47-57, 1984. 13 S. W. Kim, S. Park, and W. W. Chu. An index-based approach for similarity search supporting time warping in large sequence databases. In Proc. IEEE ICDE, pages 607-614, 2001. 14 S. Park, W. W. Chu, J. Yoon, and C. Hsu. Efficient searches for similar subsequences of different lengths in sequence databases. In Proc. IEEE ICDE, pages 23-32, 2000. 18 T. K. Sellis, N. Roussopoulos, and C. Faloutsos. The R+-tree: A dynamic index for multi-dimensional objects. In Proc. VLDB, pages 507-518, 1987. 19 K. Shim, R. Srikant, and R. Agrawal. High-dimensional similarity joins. In Proc. ICDE, pages 301-311, 1997. 21 B.-K. Yi, H. V. Jagadish, and C. Faloutsos. Efficient retrieval of similar time sequences under time warping. In IEEE ICDE, pages 201-208, 1998. CITINGS 2
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