On Products of Closed Subsets in Free Groups
arXiv:1906.07275
Abstract
We present examples of closed subsets of a free group such that their product is not closed in the profinite topology. We discuss how to characterize a subset of a free group which is closed in the profinite topology and its product with any finitely generated subgroup of a free group is also closed in the profinite topology.
arXiv admin note: text overlap with arXiv:1709.06542