Remeslennikov’s conjecture (profinite rigidity of free groups)
Prove that if a residually finite group has the same set of finite quotients as a free group of rank at least two, then it is isomorphic to that free group.
References
A major open problem in group theory is Remeslennikov's conjecture: if $G$ is a residually finite group with the same finite quotients as a free group, is $G$ necessarily free?
— The theory of one-relator groups: history and recent progress
(2501.18306 - Linton et al., 30 Jan 2025) in Section 7.2 (Residually nilpotent and parafree one‑relator groups)