Let x0 of type ι be given.
Let x1 of type ι be given.
Apply PNoLtI2 with
SNoLev x0,
SNoLev x1,
λ x2 . x2 ∈ x0,
λ x2 . x2 ∈ x1 leaving 3 subgoals.
The subproof is completed by applying H0.
The subproof is completed by applying H1.
The subproof is completed by applying H2.