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: For all y_2, if y_2 were a writer, then y_2 is a police officer. For all y_2, if y_2 were a police officer, then y_2 is a nurse. There is at least one y_2 for which if y_2 were a nurse, then y_2 is a writer.
For all y_2, if y_2 were a writer, then y_2 is a nurse can be inferred via the universal transitivity rule. There is at least one y_2 for which if y_2 were a nurse, then y_2 is a police officer can be inferred via the existential transitivity rule. There is at least one y_2 for which if y_2 were a police officer, then y_2 is a writer can be inferred via the existential transitivity rule.