Consider the following premises. There is at least one x_6 for which if x_6 takes a plane, then x_6 is sleeping. For all x_6, if x_6 sleeps, then x_6 is taking a plane. For all x_6, x_6 will play squash or x_6 will sleep. For all x_6, if x_6 plays squash, then x_6 is taking a plane. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_6 for which x_6 will take a plane.
 From the fact that there is at least one x_6 for which if x_6 takes a plane, then x_6 is sleeping, and that for all x_6, if x_6 sleeps, then x_6 is taking a plane we can infer that there is at least one x_6 for which x_6 will take a plane if and only if x_6 will sleep via existential biconditional introduction. From the fact that there is at least one x_6 for which x_6 will take a plane if and only if x_6 will sleep we can infer that there is at least one x_6 for which if x_6 sleeps, then x_6 is taking a plane via existential biconditional elimination. Finally, from the fact that for all x_6, if x_6 plays squash, then x_6 is taking a plane, that there is at least one x_6 for which if x_6 sleeps, then x_6 is taking a plane, and that for all x_6, x_6 will play squash or x_6 will sleep we can infer that there is at least one x_6 for which x_6 will take a plane via existential disjunction elimination. Therefore, the answer is yes.