Do the page "The ZFC Axioms" contain errors? I can't understand the following proposition: ∃y∀z(∃w(z ∈ w ∧ w ∈ x) ⇒ z ∈ y) Shouldn't it be: ∃y∀z(∃w(z ∈ w ∧ w

Do the page "The ZFC Axioms" contain errors? I can't understand the following proposition: ∃y∀z(∃w(z ∈ w ∧ w ∈ x) ⇒ z ∈ y) Shouldn't it be: ∃y∀z(∃w(z ∈ w ∧ w ∈ y) ⇒ z ∈ y)