Consider the following premises. William is sad if and only if it is snowing. For all x_13, x_13 is bored or x_13 is a janitor. If Jessica were bored, then it is snowing. William is not sad. Can we infer the following from them? If we can, name the inference rule being used: Jessica is not a janitor.
 From the fact that for all x_13, x_13 is bored or x_13 is a janitor we can infer that Jessica is bored or Jessica is a janitor via universal instantiation. From the fact that William is sad if and only if it is snowing, and that William is not sad we can infer that it is not snowing via biconditional elimination. From the fact that if Jessica were bored, then it is snowing, and that it is not snowing we can infer that Jessica is not bored via modus tollens. Finally, from the fact that Jessica is bored or Jessica is a janitor, and that Jessica is not bored we can infer that Jessica is a janitor via disjunctive syllogism, which contradicts that Jessica is not a janitor. Therefore, the answer is no.