 The comprehension axiom asserts that for any uniform formula \(\phi(x)\) in which all parameters (free variables other than \(x\)) are regular, there is an object \(A\), for which we use the notation \(\{x \mid \phi(x)\}\), such that \(\forall x ((x \in A \equiv \phi^*) \amp (x \varepsilon A \equiv \phi))\).