Pro-Hall $R$-groups and groups discriminated by the free pro-$p$ group

Abstract

In this note we introduce pro-Hall $R$-groups as inverse limits of Hall $R$-groups and show that for the binomial closure $S^{bin}$ of any ring $S$ discriminated by $\mathbb{Z}_p$, the free pro-Hall $S^{bin}$-group $\mathbb{F}(A,S^{bin})$ is fully residually free pro-$p$. Furthermore, we prove that any finite set of elements in $\mathbb{F}(A,S^{bin})$ defines a pro-$p$ subgroup and so an irreducible coordinate group over the free pro-$p$ group.