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