Infinitesimal containment conjectures for congruence completions

From papers

In the first case, let Γ=SL2(Z)\Gamma=\operatorname{SL}_2(\mathbb{Z}) and let pp be any prime. In the second case, let Γ\Gamma be a cocompact arithmetic lattice of the second type in SL2(C)\operatorname{SL}_2(\mathbb{C}), so that Γ\Gamma does not intersect any conjugate HH of SL2(R)\operatorname{SL}_2(\mathbb{R}) as a lattice in HH, and let Γ^c\widehat{\Gamma}^{c} be its congruence completion. Congruence-completion infinitesimal containment conjectures. In the first case,

(SL2(Zp),μ)infSL2(Z).(\operatorname{SL}_2(\mathbb{Z}_p),\mu)\xhookrightarrow{\operatorname{inf}}\operatorname{SL}_2(\mathbb{Z}).

In the second case,

(Γ^c,μ)infΓ.(\widehat{\Gamma}^{c},\mu)\xhookrightarrow{\operatorname{inf}}\Gamma.

These are further specializations of the non-amenable image criterion for compact actions, and the source gives no resolution.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Mikołaj Frączyk, “Infinitesimal containment and sparse factors of iid”, arXiv:2512.09301 (2025).

Solutions 0

No solutions have been posted yet.