Consider the following premises. For all y_4, y_4 is happy if and only if y_4 will make tea. Jennifer is making tea. Can we infer the following from them? If we can, name the inference rule being used: Jennifer is not happy.
 From the fact that for all y_4, y_4 is happy if and only if y_4 will make tea we can infer that Jennifer is happy if and only if Jennifer is making tea via universal instantiation. From the fact that Jennifer is happy if and only if Jennifer is making tea we can infer that if Jennifer makes tea, then Jennifer is happy via biconditional elimination. Finally, from the fact that if Jennifer makes tea, then Jennifer is happy, and that Jennifer is making tea we can infer that Jennifer is happy via modus ponens, which contradicts that Jennifer is not happy. Therefore, the answer is no.