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_4: R_3(x_4). exists x_4: P_4(x_4) -> U(x_4). forall x_4: P_4(x_4).
exists x_4: U(x_4) can be inferred via the existential modus ponens rule. forall x_4: R_3(x_4) and P_4(x_4) can be inferred via the universal conjunction rule. forall x_4: P_4(x_4) and R_3(x_4) can be inferred via the universal conjunction rule.