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_4: T(y_4) -> U_1(y_4). exists y_4: T(y_4). forall y_4: U(y_4) -> S(y_4). forall y_4: U(y_4).
forall y_4: S(y_4) can be inferred via the universal modus ponens rule. exists y_4: U_1(y_4) can be inferred via the existential modus ponens rule. exists y_4: T(y_4) and U(y_4) can be inferred via the existential conjunction rule. exists y_4: U(y_4) and T(y_4) can be inferred via the existential conjunction rule.