Let x0 of type ι be given.
Apply SNoLev_ordinal with
x0.
The subproof is completed by applying H0.
Apply SNo_PSNo with
ordsucc (SNoLev x0),
λ x1 . or (x1 ∈ x0) (x1 = SNoLev x0).
Apply ordinal_ordsucc with
SNoLev x0.
The subproof is completed by applying L1.