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_6: P_2(x_6) -> T(x_6). forall x_6: ~P(x_6). forall x_6: T(x_6) -> P_2(x_6). forall x_6: P_2(x_6) -> P(x_6).
forall x_6: ~P_2(x_6) can be inferred via the universal modus tollens rule. forall x_6: T(x_6) -> P(x_6) can be inferred via the universal transitivity rule. exists x_6: P_2(x_6) <-> T(x_6) can be inferred via the existential biconditional introduction rule. exists x_6: T(x_6) <-> P_2(x_6) can be inferred via the existential biconditional introduction rule.