Tight Lower Bounds for Locally Differentially Private Selection
Abstract
We prove a tight lower bound (up to constant factors) on the sample complexity of any non-interactive local differentially private protocol for optimizing a linear function over the simplex. This lower bound also implies a tight lower bound (again, up to constant factors) on the sample complexity of any non-interactive local differentially private protocol implementing the exponential mechanism. These results reveal that any local protocol for these problems has exponentially worse dependence on the dimension than corresponding algorithms in the central model. Previously, Kasiviswanathan et al. (FOCS 2008) proved an exponential separation between local and central model algorithms for PAC learning the class of parity functions. In contrast, our lower bound are quantitatively tight, apply to a simple and natural class of linear optimization problems, and our techniques are arguably simpler.
Cite
@article{arxiv.1802.02638,
title = {Tight Lower Bounds for Locally Differentially Private Selection},
author = {Jonathan Ullman},
journal= {arXiv preprint arXiv:1802.02638},
year = {2021}
}
Comments
The results in this paper have been subsumed by: Alexander Edmonds, Aleksandar Nikolov, Jonathan Ullman. "The Power of Factorization Mechanisms in Local and Central Differential Privacy." STOC 2020 [arXiv:1911.08339]. Please cite that paper for the relevant results