Let x0 of type ι → (ι → ι → ι) → (ι → ι → ι) → (ι → ι → ο) → ι → ι → ι be given.
Let x1 of type ι be given.
Let x2 of type ι → ι → ι be given.
Let x3 of type ι → ι → ι be given.
Let x4 of type ι → ι → ο be given.
Let x5 of type ι be given.
Let x6 of type ι be given.
Assume H0:
∀ x7 : ι → ι → ι . (∀ x8 . x8 ∈ x1 ⟶ ∀ x9 . x9 ∈ x1 ⟶ x2 x8 x9 = x7 x8 x9) ⟶ ∀ x8 : ι → ι → ι . (∀ x9 . x9 ∈ x1 ⟶ ∀ x10 . x10 ∈ x1 ⟶ x3 x9 x10 = x8 x9 x10) ⟶ ∀ x9 : ι → ι → ο . (∀ x10 . x10 ∈ x1 ⟶ ∀ x11 . x11 ∈ x1 ⟶ iff (x4 x10 x11) (x9 x10 x11)) ⟶ x0 x1 x7 x8 x9 x5 x6 = x0 x1 x2 x3 x4 x5 x6.