Right-angled Artin pro-$p$ groups

Let $p$ be a prime. The right-angled Artin pro-$p$ group $G_Γ$ associated to a fnite simplicial graph $Γ$ is the pro-$p$ completion of the right-angled Artin group associated to $Γ$. We prove that the following assertions are equivalent: (i) no induced subgraph of $Γ$ is a square or a line with four vertices (a path of length 3); (ii) every closed subgroup of $G_Γ$ is itself a right-angled Artin pro-$p$ group (possibly infinitely generated); (iii) $G_Γ$ is a Bloch-Kato pro-$p$ group; (iv) every closed subgroup of $G_Γ$ has torsion free abelianization; (v) $G_Γ$ occurs as the maximal pro-$p$ Galois group $G_K(p)$ of some field $K$ containing a primitive $p$th root of unity; (vi) $G_Γ$ can be constructed from $\mathbb{Z}_p$ by iterating two group theoretic operations, namely, direct products with $\mathbb{Z}_p$ and free pro-$p$ products. This settles in the affirmative a conjecture of Quadrelli and Weigel. Also, we show that the Smoothness Conjecture of De Clercq and Florens holds for right-angled Artin pro-$p$ groups. Moreover, we prove that $G_Γ$ is coherent if and only if each circuit of $Γ$ of length greater than three has a chord.

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