Let x0 of type ι be given.
Let x1 of type ι be given.
Apply unknownprop_6d861aa069d3c6b52ea4a1626e236a28ccef38ff01ec7a48d612e144c66b13b6 with
λ x2 x3 : ι → ι → ο . x3 ((λ x4 x5 . Inj1 (setsum x4 x5)) ((λ x4 x5 . Inj1 (setsum x4 x5)) (Inj0 0) x0) x1) x0.
Let x2 of type ι → ι → ο be given.
The subproof is completed by applying H3 with x0, x1.