Consider the following premises. If Charles drives a car, then Patricia is working. If Patricia works, then Charles is driving a car. Charles is not driving a car. Can we infer the following from them? If we can, name the inference rule being used: Patricia is working.
 From the fact that if Patricia works, then Charles is driving a car, and that if Charles drives a car, then Patricia is working we can infer that Patricia is working if and only if Charles is driving a car via biconditional introduction. Finally, from the fact that Patricia is working if and only if Charles is driving a car, and that Charles is not driving a car we can infer that Patricia is not working via biconditional elimination, which contradicts that Patricia is working. Therefore, the answer is no.