,
Pasin Manurangsi
Creative Commons Attribution 4.0 International license
Steinke [2025] recently asked the following intriguing open question: Can we solve the differentially private selection problem with nearly-optimal error by only (adaptively) invoking Gaussian mechanism on low-sensitivity queries? We resolve this question positively. In particular, for a candidate set 𝒴, we achieve error guarantee of Õ(log |𝒴|), which is within a factor of (log log |𝒴|)^{O(1)} of the exponential mechanism [McSherry and Talwar, 2007]. This improves on Steinke’s mechanism which achieves an error of O(log^{3/2} |𝒴|).
@InProceedings{leeman_et_al:LIPIcs.FORC.2026.4,
author = {Leeman, Ethan and Manurangsi, Pasin},
title = {{Nearly-Optimal Private Selection via Gaussian Mechanism}},
booktitle = {7th Symposium on Foundations of Responsible Computing (FORC 2026)},
pages = {4:1--4:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-419-2},
ISSN = {1868-8969},
year = {2026},
volume = {368},
editor = {Lin, Huijia (Rachel)},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FORC.2026.4},
URN = {urn:nbn:de:0030-drops-259750},
doi = {10.4230/LIPIcs.FORC.2026.4},
annote = {Keywords: Differentially Private Selection, Gaussian Mechanism}
}