Let x0 of type ι be given.
Let x1 of type ι be given.
Assume H2: x1 ∈ x0.
Apply ZF_closed_E with
x0,
0 ∈ x0 leaving 2 subgoals.
The subproof is completed by applying H1.
Apply H4 with
x1.
The subproof is completed by applying H2.
Apply H0 with
prim4 x1,
0 leaving 2 subgoals.
The subproof is completed by applying L6.
The subproof is completed by applying Empty_In_Power with x1.