What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If William drives a car, then Karen is a doctor. If Karen were a doctor, then William is driving a car.
William is driving a car if and only if Karen is a doctor can be inferred via the biconditional introduction rule. Karen is a doctor if and only if William is driving a car can be inferred via the biconditional introduction rule.