Probabilistic Burnside groups

Abstract

We prove that there exists a finitely generated group that satisfies a group law with probability 1 but does not satisfy any group law. More precisely, we construct a finitely generated group G in which the probability that a random element chosen uniformly from a finite ball in its Cayley graph, or via any non-degenerate random walk, satisfies the group law x^k=1 for some (fixed) integer k, tends to 1. Yet, G contains a non-abelian free subgroup, and therefore G does not satisfy any group law. In particular, this answers two questions of Amir, Blachar, Gerasimova, and Kozma.