Let x0 of type ι be given.
Let x1 of type ι be given.
Apply SepI with
SNoS_ (SNoLev x0),
λ x2 . SNoLt x2 x0,
x1 leaving 2 subgoals.
Apply SNoS_I2 with
x1,
x0 leaving 3 subgoals.
The subproof is completed by applying H1.
The subproof is completed by applying H0.
The subproof is completed by applying H2.
The subproof is completed by applying H3.