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: exists x_2: R_2(x_2) -> P_4(x_2). forall x_2: ~R_2(x_2). forall x_2: R_2(x_2) <-> P_4(x_2).
forall x_2: R_2(x_2) -> P_4(x_2) can be inferred via the universal biconditional elimination rule. forall x_2: P_4(x_2) -> R_2(x_2) can be inferred via the universal biconditional elimination rule. forall x_2: ~P_4(x_2) can be inferred via the universal biconditional elimination rule.