Proofgold Proof

pf
Let x0 of type ι be given. Let x1 of type ι be given. Let x2 of type ι be given. Let x3 of type ι be given. The subproof is completed by applying PNoEq_tra_ with x0, λ x4 . x4 ∈ x1, λ x4 . x4 ∈ x2, λ x4 . x4 ∈ x3. ■