What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Mary is a lawyer if and only if John is a police officer. John is a police officer if and only if it is raining.
If Mary were a lawyer, then John is a police officer. If John were a police officer, then it is raining. If John were a police officer, then Mary is a lawyer. If it rains, then John is a police officer.