Let x0 of type ι be given.
Let x1 of type ι be given.
Apply H0 with
λ x2 . x2 = pack_e x0 x1 ⟶ x1 ∈ x0 leaving 2 subgoals.
Let x2 of type ι be given.
Let x3 of type ι be given.
Assume H1: x3 ∈ x2.
Apply pack_e_inj with
x2,
x0,
x3,
x1,
x1 ∈ x0 leaving 2 subgoals.
The subproof is completed by applying H2.
Assume H3: x2 = x0.
Assume H4: x3 = x1.
Apply H3 with
λ x4 x5 . x1 ∈ x4.
Apply H4 with
λ x4 x5 . x4 ∈ x2.
The subproof is completed by applying H1.
Let x2 of type ι → ι → ο be given.
The subproof is completed by applying H1.