Let x0 of type ι → ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Assume H0: x1 ⊆ x2.
Let x3 of type ι be given.
Assume H1: x3 ∈ {x0 x4|x4 ∈ x1}.
Apply ReplE_impred with
x1,
x0,
x3,
x3 ∈ prim5 x2 x0 leaving 2 subgoals.
The subproof is completed by applying H1.
Let x4 of type ι be given.
Assume H2: x4 ∈ x1.
Assume H3: x3 = x0 x4.
Apply H3 with
λ x5 x6 . x6 ∈ prim5 x2 x0.
Apply ReplI with
x2,
x0,
x4.
Apply H0 with
x4.
The subproof is completed by applying H2.