Consider the following premises. It is overcast. Linda is a sailor if and only if Jennifer is sad. Linda is not a sailor. Charles is a bartender if and only if Jennifer is sad. Can we infer the following from them? If we can, name the inference rule being used: Charles is a bartender.
 From the fact that Linda is a sailor if and only if Jennifer is sad, and that Linda is not a sailor we can infer that Jennifer is not sad via biconditional elimination. Finally, from the fact that Charles is a bartender if and only if Jennifer is sad, and that Jennifer is not sad we can infer that Charles is not a bartender via biconditional elimination, which contradicts that Charles is a bartender. Therefore, the answer is no.