What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y: Q(y) or R_4(y). forall y: W_4(y) -> U_4(y). exists y: Q(y) <-> U_4(y). forall y: R_4(y) -> W_4(y).
forall y: R_4(y) -> U_4(y). exists y: Q(y) -> U_4(y). exists y: U_4(y) -> Q(y).