Let x0 of type ι be given.
Let x1 of type ι → ι → 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 → ι be given.
Let x5 of type ι → ι be given.
Let x6 of type ι → ι be given.
Assume H0: ∀ x7 . x7 ∈ x0 ⟶ ∀ x8 . x8 ∈ x0 ⟶ x1 x7 x8 = x2 x7 x8.
Assume H1: ∀ x7 . x7 ∈ x0 ⟶ ∀ x8 . x8 ∈ x0 ⟶ x3 x7 x8 = x4 x7 x8.
Assume H2: ∀ x7 . x7 ∈ x0 ⟶ x5 x7 = x6 x7.
Apply L3 with
λ x7 x8 . lam 4 (λ x9 . If_i (x9 = 0) x0 (If_i (x9 = 1) (encode_b x0 x1) (If_i (x9 = 2) (encode_b x0 x3) (lam x0 x5)))) = lam 4 (λ x9 . If_i (x9 = 0) x0 (If_i (x9 = 1) x7 (If_i (x9 = 2) (encode_b x0 x4) (lam x0 x6)))).
Apply encode_b_ext with
x0,
x3,
x4.
The subproof is completed by applying H1.
Apply L4 with
λ x7 x8 . lam 4 (λ x9 . If_i (x9 = 0) x0 (If_i (x9 = 1) (encode_b x0 x1) (If_i (x9 = 2) (encode_b x0 x3) (lam x0 x5)))) = lam 4 (λ x9 . If_i (x9 = 0) x0 (If_i (x9 = 1) (encode_b x0 x1) (If_i (x9 = 2) x7 (lam x0 x6)))).
Claim L5:
lam x0 x5 = lam x0 x6Apply encode_u_ext with
x0,
x5,
x6.
The subproof is completed by applying H2.