Abstract | ||
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We consider the problem of estimating cascaded aggregates over a matrix presented as a sequence of updates in a data stream. A cascaded aggregate P 卤Q is defined by evaluating aggregate Q repeatedly over each row of the matrix, and then evaluating aggregate P over the resulting vector of values. This problem was introduced by Cormode andMuthukrishnan, PODS, 2005 [CM]. We analyze the space complexity of estimating cascaded norms on an n 拢d matrix to within a small relative error. Let Lp denote the p-th norm, where p is a non-negative integer. We abbreviate the cascaded normLk 卤Lp by Lk,p . (1) For any constant k 赂 p 赂 2, we obtain a 1-pass e O(n1隆2/kd1隆2/p )-space algorithm for estimating Lk,p . This is optimal up to polylogarithmic factors and resolves an open question of [CM] regarding the space complexity of L4,2. We also obtain 1-pass space-optimal algorithms for estimating L1,k and Lk,1. (2)We prove a space lower bound of (n1隆1/k ) on estimating Lk,0 and Lk,1, resolving an open question due to Indyk, IITK Data StreamsWorkshop (Problem 8), 2006. We also resolve two more questions of [CM] concerning Lk,2 estimation and block heavy hitter problems. Ganguly, Bansal and Dube (FAW, 2008) claimed an e O(1)-space algorithm for estimating Lk,p for any k,p 2 [0,2]. Our lower bounds show this claimis incorrect. |
Year | DOI | Venue |
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2009 | 10.1109/FOCS.2009.82 | FOCS |
Keywords | Field | DocType |
cascaded aggregate p,aggregate p,cascaded normlk,data stream space complexity,cascaded norms,cascaded aggregate,cascaded norm,open question,constant k,space algorithm,aggregate q,space complexity,approximation algorithms,level set,computational complexity,histograms,algorithm design and analysis,relative error,estimation,lower bound | Integer,Approximation algorithm,Discrete mathematics,Combinatorics,Algorithm design,Upper and lower bounds,Data stream,Matrix (mathematics),Approximation error,Mathematics,Computational complexity theory | Conference |
ISSN | Citations | PageRank |
0272-5428 | 28 | 1.01 |
References | Authors | |
21 | 2 |
Name | Order | Citations | PageRank |
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T. S. Jayram | 1 | 1373 | 75.87 |
David P. Woodruff | 2 | 2156 | 142.38 |