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_11: T(x_11) -> U(x_11). forall x_11: ~S_2(x_11). exists x_11: U(x_11) -> T(x_11). forall x_11: U(x_11) -> T(x_11). forall x_11: U(x_11) -> S_2(x_11).
forall x_11: ~U(x_11) can be inferred via the universal modus tollens rule. forall x_11: T(x_11) -> S_2(x_11) can be inferred via the universal transitivity rule. forall x_11: T(x_11) <-> U(x_11) can be inferred via the universal biconditional introduction rule. forall x_11: U(x_11) <-> T(x_11) can be inferred via the universal biconditional introduction rule. exists x_11: U(x_11) <-> T(x_11) can be inferred via the existential biconditional introduction rule. exists x_11: T(x_11) <-> U(x_11) can be inferred via the existential biconditional introduction rule.