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_5: ~S(x_5). forall x_5: S(x_5) -> T(x_5). forall x_5: T(x_5) -> S(x_5).
exists x_5: ~T(x_5) can be inferred via the existential modus tollens rule. forall x_5: S(x_5) <-> T(x_5) can be inferred via the universal biconditional introduction rule. forall x_5: T(x_5) <-> S(x_5) can be inferred via the universal biconditional introduction rule.