Let x0 of type ι be given.
Apply ordinal_In_Or_Subq with
0,
ordsucc x0,
0 ∈ ordsucc x0 leaving 4 subgoals.
The subproof is completed by applying ordinal_Empty.
Apply ordinal_ordsucc with
x0.
The subproof is completed by applying H0.
The subproof is completed by applying H1.
Apply FalseE with
0 ∈ ordsucc x0.
Apply EmptyE with
x0.
Apply H1 with
x0.
The subproof is completed by applying ordsuccI2 with x0.