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» Lower-bounding term frequency normalization
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CIKM
2011
Springer
12 years 4 months ago
Lower-bounding term frequency normalization
In this paper, we reveal a common deficiency of the current retrieval models: the component of term frequency (TF) normalization by document length is not lower-bounded properly;...
Yuanhua Lv, ChengXiang Zhai
SODA
2004
ACM
87views Algorithms» more  SODA 2004»
13 years 6 months ago
Optimal space lower bounds for all frequency moments
We prove that any one-pass streaming algorithm which ( , )-approximates the kth frequency moment Fk, for any real k = 1 and any = 1 m , must use 1 2 bits of space, where m is th...
David P. Woodruff
DIALM
2005
ACM
130views Algorithms» more  DIALM 2005»
13 years 6 months ago
On lower bounds for MAC layer contention in CSMA/CA-based wireless networks
Wireless LANs operating within unlicensed frequency bands require random access schemes such as CSMA/CA, so that wireless networks from different administrative domains (for exam...
Frank A. Zdarsky, Ivan Martinovic, Jens B. Schmitt
CIKM
2011
Springer
12 years 4 months ago
Adaptive term frequency normalization for BM25
A key component of BM25 contributing to its success is its sub-linear term frequency (TF) normalization formula. The scale and shape of this TF normalization component is controll...
Yuanhua Lv, ChengXiang Zhai
STOC
2005
ACM
143views Algorithms» more  STOC 2005»
14 years 5 months ago
Optimal approximations of the frequency moments of data streams
We give a 1-pass ~O(m1-2/k )-space algorithm for computing the k-th frequency moment of a data stream for any real k > 2. Together with the lower bounds of [1, 2, 4], this reso...
Piotr Indyk, David P. Woodruff