Consider the following premises. It is sunny if and only if Jessica is playing a game. Susan is climbing a mountain. For all x_14, x_14 will not play a game. Can we infer the following from them? If we can, name the inference rule being used: It is sunny.
 From the fact that for all x_14, x_14 will not play a game we can infer that Jessica is not playing a game via universal instantiation. Finally, from the fact that it is sunny if and only if Jessica is playing a game, and that Jessica is not playing a game we can infer that it is not sunny via biconditional elimination, which contradicts that It is sunny. Therefore, the answer is no.