Let x0 of type ι be given.
Apply H0 with
struct_r x0.
Assume H2:
unpack_r_o x0 (λ x1 . λ x2 : ι → ι → ο . and (∀ x3 . x3 ∈ x1 ⟶ ∀ x4 . x4 ∈ x1 ⟶ x2 x3 x4 ⟶ x2 x4 x3) (∀ x3 . x3 ∈ x1 ⟶ ∀ x4 . x4 ∈ x1 ⟶ ∀ x5 . x5 ∈ x1 ⟶ x2 x3 x4 ⟶ x2 x4 x5 ⟶ x2 x3 x5)).
The subproof is completed by applying H1.