Monotonicity Testing of High-Dimensional Distributions with Subcube Conditioning
Deeparnab Chakrabarty, Xi Chen, Simeon Ristic, C. Seshadhri, Erik Waingarten
TL;DR
This work resolves the query complexity of monotonicity testing for high-dimensional distributions under subcube conditioning, showing a near-tight ${\tildeΘ(n/\varepsilon^2)}$ bound and introducing a real-valued directed isoperimetric framework to analyze distribution testers. The core method centers on an edge tester that leverages 1-dimensional subcube conditioning and a novel $(L^1,\ell^2)$-Talagrand inequality to relate distance to monotonicity to detectable edge biases. The authors also establish a matching lower bound via moment-matching constructions on product distributions, and extend the analysis to uniformity testing under the monotone promise, proving a ${\tildeΩ(\sqrt{n}/\varepsilon^2)}$ bound. Overall, the results demonstrate that monotonicity does not materially improve uniformity testing in this model, and they introduce tools that may be of independent interest for high-dimensional distribution testing.
Abstract
We study monotonicity testing of high-dimensional distributions on $\{-1,1\}^n$ in the model of subcube conditioning, suggested and studied by Canonne, Ron, and Servedio~\cite{CRS15} and Bhattacharyya and Chakraborty~\cite{BC18}. Previous work shows that the \emph{sample complexity} of monotonicity testing must be exponential in $n$ (Rubinfeld, Vasilian~\cite{RV20}, and Aliakbarpour, Gouleakis, Peebles, Rubinfeld, Yodpinyanee~\cite{AGPRY19}). We show that the subcube \emph{query complexity} is $\tildeΘ(n/\varepsilon^2)$, by proving nearly matching upper and lower bounds. Our work is the first to use directed isoperimetric inequalities (developed for function monotonicity testing) for analyzing a distribution testing algorithm. Along the way, we generalize an inequality of Khot, Minzer, and Safra~\cite{KMS18} to real-valued functions on $\{-1,1\}^n$. We also study uniformity testing of distributions that are promised to be monotone, a problem introduced by Rubinfeld, Servedio~\cite{RS09} , using subcube conditioning. We show that the query complexity is $\tildeΘ(\sqrt{n}/\varepsilon^2)$. Our work proves the lower bound, which matches (up to poly-logarithmic factors) the uniformity testing upper bound for general distributions (Canonne, Chen, Kamath, Levi, Waingarten~\cite{CCKLW21}). Hence, we show that monotonicity does not help, beyond logarithmic factors, in testing uniformity of distributions with subcube conditional queries.
