Let x0 of type ι → ο be given.
Let x1 of type ι → ι → ι → ο be given.
Let x2 of type ι → ι be given.
Let x3 of type ι → ι → ι → ι → ι → ι be given.
Assume H2: ∀ x4 x5 x6 . x0 x4 ⟶ x0 x5 ⟶ x1 x4 x5 x6 ⟶ x3 x4 x4 x5 x6 (x2 x4) = x6.
Assume H3: ∀ x4 x5 x6 . x0 x4 ⟶ x0 x5 ⟶ x1 x4 x5 x6 ⟶ x3 x4 x5 x5 (x2 x5) x6 = x6.
Assume H4: ∀ x4 x5 x6 x7 x8 x9 x10 . x0 x4 ⟶ x0 x5 ⟶ x0 x6 ⟶ x0 x7 ⟶ x1 x4 x5 x8 ⟶ x1 x5 x6 x9 ⟶ x1 x6 x7 x10 ⟶ x3 x4 x5 x7 (x3 x5 x6 x7 x10 x9) x8 = x3 x4 x6 x7 x10 (x3 x4 x5 x6 x9 x8).