Let x0 of type ι be given.
Apply H0 with
λ x1 . x1 = pack_c_e (ap x1 0) (decode_c (ap x1 1)) (ap x1 2).
Let x1 of type ι be given.
Let x2 of type (ι → ο) → ο be given.
Let x3 of type ι be given.
Assume H1: x3 ∈ x1.
Apply pack_c_e_0_eq2 with
x1,
x2,
x3,
λ x4 x5 . pack_c_e x1 x2 x3 = pack_c_e x4 (decode_c (ap (pack_c_e x1 x2 x3) 1)) (ap (pack_c_e x1 x2 x3) 2).
Apply pack_c_e_2_eq2 with
x1,
x2,
x3,
λ x4 x5 . pack_c_e x1 x2 x3 = pack_c_e x1 (decode_c (ap (pack_c_e x1 x2 x3) 1)) x4.
Apply pack_c_e_ext with
x1,
x2,
decode_c (ap (pack_c_e x1 x2 x3) 1),
x3.
Let x4 of type ι → ο be given.
Assume H2: ∀ x5 . x4 x5 ⟶ x5 ∈ x1.
Apply pack_c_e_1_eq2 with
x1,
x2,
x3,
x4,
λ x5 x6 : ο . iff (x2 x4) x5 leaving 2 subgoals.
The subproof is completed by applying H2.
The subproof is completed by applying iff_refl with x2 x4.