Consider the following premises. There is at least one x_6 for which if x_6 plays tennis, then x_6 is playing squash. For all x_6, if x_6 plays tennis, then x_6 is not a janitor. For all x_6, x_6 is a janitor. For all x_6, if x_6 plays squash, then x_6 is playing tennis. Can we infer the following from them? If we can, name the inference rule being used: For all x_6, x_6 will play squash.
 From the fact that for all x_6, if x_6 plays squash, then x_6 is playing tennis, and that there is at least one x_6 for which if x_6 plays tennis, then x_6 is playing squash we can infer that there is at least one x_6 for which x_6 will play squash if and only if x_6 will play tennis via existential biconditional introduction. From the fact that for all x_6, if x_6 plays tennis, then x_6 is not a janitor, and that for all x_6, x_6 is a janitor we can infer that for all x_6, x_6 will not play tennis via universal modus tollens. Finally, from the fact that there is at least one x_6 for which x_6 will play squash if and only if x_6 will play tennis, and that for all x_6, x_6 will not play tennis we can infer that there is at least one x_6 for which x_6 will not play squash via existential biconditional elimination, which contradicts that For all x_6, x_6 will play squash. Therefore, the answer is no.