Relative-error unateness testing
Xi Chen, Diptaksho Palit, Kabir Peshawaria, William Pires, Rocco A. Servedio, Yiding Zhang
TL;DR
This work studies relative-error unateness testing for Boolean functions f: {0,1}^n -> {0,1}, where distance is measured relative to the number of 1s in f, |f^{-1}(1)|=N. It develops two testers: a known-N one-sided non-adaptive tester with query complexity ilde{O}( abla abla log N / abla epsilon) and an unknown-N one-sided adaptive tester achieving the same order without knowledge of N. The paper also establishes lower bounds: a non-adaptive two-sided lower bound of ilde{ Omega}( log N) and a two-sided adaptive lower bound of ilde{ Omega}(( log N)^{2/3}), which together delineate the landscape in this relative-error model. The results reveal a nuanced role for sparsity N in relative-error unateness testing, including a gap between adaptive and non-adaptive regimes and between relative-error and standard-model bounds, driven by the fact that the closure under truncation concentrates action on adjacent layers rather than long hypercube paths. These findings connect to prior relative-error monotonicity results and open avenues for exploring other semantic properties under the relative-error framework.
Abstract
The model of relative-error property testing of Boolean functions has been the subject of significant recent research effort [CDH+24][CPPS25a][CPPS25b] In this paper we consider the problem of relative-error testing an unknown and arbitrary $f: \{0,1\}^n \to \{0,1\}$ for the property of being a unate function, i.e. a function that is either monotone non-increasing or monotone non-decreasing in each of the $n$ input variables. Our first result is a one-sided non-adaptive algorithm for this problem that makes $\tilde{O}(\log(N)/ε)$ samples and queries, where $N=|f^{-1}(1)|$ is the number of satisfying assignments of the function that is being tested and the value of $N$ is given as an input parameter to the algorithm. Building on this algorithm, we next give a one-sided adaptive algorithm for this problem that does not need to be given the value of $N$ and with high probability makes $\tilde{O}(\log(N)/ε)$ samples and queries. We also give lower bounds for both adaptive and non-adaptive two-sided algorithms that are given the value of $N$ up to a constant multiplicative factor. In the non-adaptive case, our lower bounds essentially match the complexity of the algorithm that we provide.
