A Tolerant Independent Set Tester
Cameron Seth
TL;DR
This work addresses tolerant testing of the $\rho$-IndepSet property in dense graphs, achieving a near-optimal sample complexity of $\widetilde{O}(\rho^3/\epsilon^2)$ with a tolerant gap $(\epsilon/(c\log^4(1/\epsilon)),\epsilon)$. The main technical advance is a graph container lemma for sparse subgraphs, built from a fingerprint/revision framework, enabling containment guarantees even when induced subgraphs are only sparsely connected. The authors leverage this lemma to design a tolerant tester that matches the non-tolerant upper bound up to logarithmic factors and to generalize counting arguments for independent sets to counting sparse subgraphs in regular graphs. Together, these results push the frontier of tolerant graph property testing in the dense setting and open pathways to broader applications of sparse-subgraph containers, including counting problems in regular graphs.
Abstract
We give nearly optimal bounds on the sample complexity of $(\widetildeΩ(ε),ε)$-tolerant testing the $ρ$-independent set property in the dense graph setting. In particular, we give an algorithm that inspects a random subgraph on $\widetilde{O}(ρ^3/ε^2)$ vertices and, for some constant $c,$ distinguishes between graphs that have an induced subgraph of size $ρn$ with fewer than $\fracε{c \log^4(1/ε)} n^2$ edges from graphs for which every induced subgraph of size $ρn$ has at least $εn^2$ edges. Our sample complexity bound matches, up to logarithmic factors, the recent upper bound by Blais and Seth (2023) for the non-tolerant testing problem, which is known to be optimal for the non-tolerant testing problem based on a lower bound by Feige, Langberg and Schechtman (2004). Our main technique is a new graph container lemma for sparse subgraphs instead of independent sets. We also show that our new lemma can be used to generalize one of the classic applications of the container method, that of counting independent sets in regular graphs, to counting sparse subgraphs in regular graphs.
