Proofgold Proof

pf
Let x0 of type ι be given. Let x1 of type ι be given. Let x2 of type ι be given. Assume H0: x2 ∈ x0. Assume H1: nIn x2 x1. Apply SepI with x0, λ x3 . nIn x3 x1, x2 leaving 2 subgoals. The subproof is completed by applying H0. The subproof is completed by applying H1. ■