What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: forall x_3: P(x_3) -> S_4(x_3). ~P(c_2). q -> S_4(c_2). forall x_3: S_4(x_3) -> P(x_3).
forall x_3: P(x_3) <-> S_4(x_3) can be inferred via the universal biconditional introduction rule. forall x_3: S_4(x_3) <-> P(x_3) can be inferred via the universal biconditional introduction rule.