期刊名称:Electronic Colloquium on Computational Complexity
印刷版ISSN:1433-8092
出版年度:2010
卷号:2010
出版社:Universität Trier, Lehrstuhl für Theoretische Computer-Forschung
摘要:For every fixed finite field \Fq, p(01−1q) and 0, we prove that with high probability a random subspace C of
\Fnq of dimension (1−Hq(p)−)n has the
property that every Hamming ball of radius pn has at most
O(1) codewords.
This answers a basic open question concerning the list-decodability
of linear codes, showing that a list size of O(1)
suffices to have rate within of the ``capacity''
1−Hq(p). This matches up to constant factors the list-size
achieved by general random codes, and gives an exponential improvement
over the best previously known list-size bound of qO(1) .
The main technical ingredient in our proof is a strong upper bound
on the probability that random vectors chosen from a Hamming
ball centered at the origin have too many (more than ())
vectors from their linear span also belong to the ball.
关键词:list-decoding, random linear codes, Sauer-Shelah lemma