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_5: S_3(x_5) -> U_4(x_5). forall x_5: W_4(x_5) -> S_3(x_5). exists x_5: U_4(x_5) or W_4(x_5). forall x_5: U_4(x_5) -> S_3(x_5).
forall x_5: W_4(x_5) -> U_4(x_5) can be inferred via the universal transitivity rule. exists x_5: S_3(x_5) can be inferred via the existential disjunction elimination rule. forall x_5: S_3(x_5) <-> U_4(x_5) can be inferred via the universal biconditional introduction rule. forall x_5: U_4(x_5) <-> S_3(x_5) can be inferred via the universal biconditional introduction rule.