What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one y for which y is an astronaut if and only if y is a police officer. For all y, y is an astronaut.
There is at least one y for which if y were an astronaut, then y is a police officer. There is at least one y for which if y were a police officer, then y is an astronaut.