The parity search problem
Abstract
We prove that for any positive integers and there exists a collection consisting of subsets of such that for any two distinct subsets and of whose size is at most there is an index for which and have different parity. Here we think of as fixed whereas is thought of as tending to infinity, and the base of the logarithm is . Translated into the language of combinatorial search theory, this tells us that queries suffice to identify up to marked items from a totality of items if the answers one gets are just whether an even or an odd number of marked elements has been queried, even if the search is performed non-adaptively. Since the entropy method easily yields a matching lower bound for the adaptive version of this problem, our result is asymptotically best possible. This answers a question posed by D\'aniel Gerbner and Bal\'azs Patk\'os in Gyula O.H. Katona's Search Theory Seminar at the R\'enyi institute.
Cite
@article{arxiv.1603.06164,
title = {The parity search problem},
author = {Christian Reiher},
journal= {arXiv preprint arXiv:1603.06164},
year = {2016}
}