∀R { { ∀[ψ], t: R([ψ],t) ↔ ([ψ] = “xi ∈ xj” ∧ t(xi) ∈ t(xj)) ∨ ([ψ] = “xi = xj” ∧ t(xi) = t(xj)) ∨ ([ψ] = “(¬θ)” ∧ ¬R([θ], t)) ∨ ([ψ] = “(θ∧ξ)” ∧ R([θ], t) ∧ R([ξ], t)) ∨ ([ψ] = “∃xi(θ)” ∧ ∃t′: R([θ], t′)) (where t′ is a copy of t with xi changed) } ⇒ R([ϕ],s) }