Space/time trade-offs in hash coding with allowable errors
Communications of the ACM
Randomness conductors and constant-degree lossless expanders
STOC '02 Proceedings of the thiry-fourth annual ACM symposium on Theory of computing
SIAM Journal on Computing
Data structures for storing small sets in the bitprobe model
ESA'10 Proceedings of the 18th annual European conference on Algorithms: Part II
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An adaptive (n, m, s, t)-scheme is a deterministic scheme for encoding a vector X of m bits with at most n ones by a vector Y of s bits, so that any bit of X can be determined by t adaptive probes to Y. A non-adaptive (n, m, s, t)-scheme is defined analogously. The study of such schemes arises in the investigation of the static membership problem in the bitprobe model. Answering a question of Buhrman, Miltersen, Radhakrishnan and Venkatesh [SICOMP 2002] we present adaptive (n, m, s, 2) schemes with s m for all n satisfying 4n2 + 4n m and adaptive (n, m, s, 2) schemes with s = o(m) for all n = o(log m). We further show that there are adaptive (n, m, s, 3)-schemes with s = o(m) for all n = o(m), settling a problem of Radhakrishnan, Raman and Rao [ESA 2001], and prove that there are non-adaptive (n, m, s, 4)-schemes with s = o(m) for all n = o(m). Therefore, three adaptive probes or four non-adaptive probes already suffice to obtain a significant saving in space compared to the total length of the input vector. Lower bounds are discussed as well.