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 y: U(y) <-> T(y). forall y: T(y) -> S(y). forall y: S(y) -> U(y).
forall y: T(y) -> U(y) can be inferred via the universal transitivity rule. exists y: U(y) -> T(y) can be inferred via the existential biconditional elimination rule. exists y: T(y) -> U(y) can be inferred via the existential biconditional elimination rule.