Abelian groups are polynomially stable

In recent years, there has been a considerable amount of interest in stability of equations and their corresponding groups. Here, we initiate the systematic study of the quantitative aspect of this theory. We develop a novel method, inspired by the Ornstein-Weiss quasi-tiling technique, to prove that abelian groups are polynomially stable with respect to permutations, under the normalized Hamming metrics on the groups $\mathrm{Sym}(n)$. In particular, this means that there exists $D\ge 1$ such that for $A,B\in \operatorname{Sym}(n)$,if$AB$is$\delta$-closeto$BA$,then$A$and$B$are$\epsilon$-closetoacommutingpairofpermutations,where$\epsilon\leq O(\delta^{1/D})$. We also observe a property-testing reformulation of this result, yielding efficient testers for certain permutation properties.