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: U_2(y) or S_4(y). forall y: P(y) <-> T(y). forall y: S_4(y) -> R_1(y). forall y: R_1(y) -> P(y). exists y: U_2(y) -> T(y).
forall y: S_4(y) -> P(y) can be inferred via the universal transitivity rule. forall y: P(y) -> T(y) can be inferred via the universal biconditional elimination rule. forall y: T(y) -> P(y) can be inferred via the universal biconditional elimination rule.