Title
Explicit Dimension Reduction and Its Applications
Abstract
We construct a small set of explicit linear transformationsmapping R^n to R^t, where t=O(log (\gamma^{-1}) \eps^{-2} ), suchthat the L_2 norm of any vector in R^n is distorted by atmost 1\pm \eps in at least a fraction of 1-\gamma of thetransformations in the set. Albeit the tradeoff between thesize of the set and the success probability is sub-optimal comparedwith probabilistic arguments, we nevertheless are able to applyour construction to a number of problems. In particular, we use itto construct an \eps-sample (or pseudo-random generator) forlinear threshold functions on S^{n-1}, for \eps = o(1). Wealso use it to construct an \eps-sample for spherical digons inS^{n-1}, for \eps=o(1). This construction leads to anefficient oblivious derandomization of the Goemans-Williamson MAXCUT algorithm and similar approximation algorithms (i.e., weconstruct a small set of hyperplanes, such that for any instancewe can choose one of them to generate a good solution). Our technique for constructing \eps-sample for linear thresholdfunctions on the sphere is considerably different than previoustechniques that rely on k-wise independent sample spaces.
Year
DOI
Venue
2011
10.1137/110828812
SIAM Journal on Computing
Keywords
DocType
Volume
dimension reduction,pseudorandom generator,max cut
Conference
41
Issue
ISSN
Citations 
1
1093-0159
10
PageRank 
References 
Authors
0.59
26
3
Name
Order
Citations
PageRank
Zohar S. Karnin126620.98
Yuval Rabani22265274.98
Amir Shpilka3109564.27