,
Anindya De
,
Yizhi Huang
,
Shivam Nadimpalli
,
Rocco A. Servedio
,
Tianqi Yang
Creative Commons Attribution 4.0 International license
The relative-error property testing model was introduced in [Chen et al., 2024] to facilitate the study of property testing for "sparse" Boolean-valued functions, i.e. ones for which only a small fraction of all input assignments satisfy the function. In this framework, the distance from the unknown target function f that is being tested to a function g is defined as Vol(f△g)/Vol(f), where the numerator is the fraction of inputs on which f and g disagree and the denominator is the fraction of inputs that satisfy f.
Recent work [Chen et al., 2026] has shown that over the Boolean domain {0,1}ⁿ, any relative-error testing algorithm for the fundamental class of {halfspaces} (i.e. linear threshold functions) must make Ω(log n) oracle calls. In this paper we complement the [Chen et al., 2026] lower bound by showing that halfspaces can be relative-error tested over ℝⁿ under the standard N(0,I_n) Gaussian distribution using a sublinear number of oracle calls - in particular, substantially fewer than would be required for learning. Our results use a wide range of tools including Hermite analysis, Gaussian isoperimetric inequalities, and geometric results on noise sensitivity and surface area.
@InProceedings{chen_et_al:LIPIcs.ICALP.2026.61,
author = {Chen, Xi and De, Anindya and Huang, Yizhi and Nadimpalli, Shivam and Servedio, Rocco A. and Yang, Tianqi},
title = {{Sublinear-Query Relative-Error Testing of Halfspaces}},
booktitle = {53rd International Colloquium on Automata, Languages, and Programming (ICALP 2026)},
pages = {61:1--61:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-428-4},
ISSN = {1868-8969},
year = {2026},
volume = {374},
editor = {Bhattacharya, Sayan and Nanongkai, Danupon and Benedikt, Michael and Puppis, Gabriele},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2026.61},
URN = {urn:nbn:de:0030-drops-264508},
doi = {10.4230/LIPIcs.ICALP.2026.61},
annote = {Keywords: Property testing, relative-error testing, halfspaces, Gaussian space}
}