Let x0 of type ι be given.
Let x1 of type (ι → ο) → ο be given.
Let x2 of type ι → ι → ι be given.
Assume H0: ∀ x3 . x3 ∈ x0 ⟶ ∀ x4 . x4 ∈ x0 ⟶ x2 x3 x4 ∈ x0.
Let x3 of type ι → ι be given.
Assume H1: ∀ x4 . x4 ∈ x0 ⟶ x3 x4 ∈ x0.
Let x4 of type ι be given.
Assume H2: x4 ∈ x0.
Let x5 of type ι → ο be given.
Assume H3:
∀ x6 . ∀ x7 : (ι → ο) → ο . ∀ x8 : ι → ι → ι . (∀ x9 . x9 ∈ x6 ⟶ ∀ x10 . x10 ∈ x6 ⟶ x8 x9 x10 ∈ x6) ⟶ ∀ x9 : ι → ι . (∀ x10 . x10 ∈ x6 ⟶ x9 x10 ∈ x6) ⟶ ∀ x10 . x10 ∈ x6 ⟶ x5 (pack_c_b_u_e x6 x7 x8 x9 x10).
Apply H3 with
x0,
x1,
x2,
x3,
x4 leaving 3 subgoals.
The subproof is completed by applying H0.
The subproof is completed by applying H1.
The subproof is completed by applying H2.