What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Richard is sad if and only if it is late. If it is late, then it is sunny. It is sunny if and only if Karen is sleeping. Karen is not sleeping.
If Richard were sad, then it is late. If it is sunny, then Karen is sleeping. If it is late, then Richard is sad. If Karen sleeps, then it is sunny. It is not sunny.