What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Karen is playing tennis if and only if Linda is a doctor. If David were sad, then Karen is playing tennis. Linda is a doctor or Karen is sleeping. Karen is sleeping if and only if David is sad.
If Karen plays tennis, then Linda is a doctor. If Karen sleeps, then David is sad. If Linda were a doctor, then Karen is playing tennis. If David were sad, then Karen is sleeping.