Consider the following premises. There is at least one x_8 for which x_8 is fast if and only if x_8 is a soldier. For all x_8, if x_8 were a soldier, then x_8 is fast. For all x_8, x_8 will not play squash. For all x_8, if x_8 were fast, then x_8 is playing squash. Can we infer the following from them? If we can, name the inference rule being used: For all x_8, x_8 is a soldier.
 From the fact that for all x_8, if x_8 were fast, then x_8 is playing squash, and that for all x_8, x_8 will not play squash we can infer that for all x_8, x_8 is not fast via universal modus tollens. From the fact that there is at least one x_8 for which x_8 is fast if and only if x_8 is a soldier we can infer that there is at least one x_8 for which if x_8 were fast, then x_8 is a soldier via existential biconditional elimination. From the fact that there is at least one x_8 for which if x_8 were fast, then x_8 is a soldier, and that for all x_8, if x_8 were a soldier, then x_8 is fast we can infer that there is at least one x_8 for which x_8 is fast if and only if x_8 is a soldier via existential biconditional introduction. Finally, from the fact that there is at least one x_8 for which x_8 is fast if and only if x_8 is a soldier, and that for all x_8, x_8 is not fast we can infer that there is at least one x_8 for which x_8 is not a soldier via existential biconditional elimination, which contradicts that For all x_8, x_8 is a soldier. Therefore, the answer is no.