Apply unknownprop_f8517820c41e80abae5090668a4d7f9c31465f066f11281cc9990a74d008bfa1 with
λ x0 : ι → ι . λ x1 . x0 (x0 (x0 (x0 (x0 x1)))).
The subproof is completed by applying unknownprop_d5dbeec732ea01f927877e2420b51cb5c68f473bf98d93e8571ddfd3f7adea18.