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