Let x0 of type ι → ι be given.
Apply Empty_eq with
{x0 x1|x1 ∈ 0}.
Let x1 of type ι be given.
Assume H0: x1 ∈ {x0 x2|x2 ∈ 0}.
Apply ReplE_impred with
0,
x0,
x1,
False leaving 2 subgoals.
The subproof is completed by applying H0.
Let x2 of type ι be given.
Assume H1: x2 ∈ 0.
Assume H2: x1 = x0 x2.
Apply EmptyE with
x2.
The subproof is completed by applying H1.