Let x0 of type ι be given.
Let x1 of type ι → ι be given.
Let x2 of type ι → ι be given.
Assume H1:
∀ x3 . x3 ∈ SNoS_ (SNoLev x0) ⟶ x1 x3 = x2 x3.
Apply nat_ind with
λ x3 . SNo_recipaux x0 x1 x3 = SNo_recipaux x0 x2 x3 leaving 2 subgoals.
Apply SNo_recipaux_0 with
x0,
x2,
λ x3 x4 . SNo_recipaux x0 x1 0 = x4.
The subproof is completed by applying SNo_recipaux_0 with x0, x1.
Let x3 of type ι be given.
Apply SNo_recipaux_S with
x0,
x1,
x3,
λ x4 x5 . x5 = SNo_recipaux x0 x2 (ordsucc x3) leaving 2 subgoals.
The subproof is completed by applying H2.