Consider the following premises. For all x_16, if x_16 drinks water, then x_16 is taking a plane. For all x_16, if x_16 plays squash, then x_16 is taking a plane. For all x_16, x_16 will go running if and only if x_16 will take a plane. There is at least one x_16 for which x_16 will play squash. Can we infer the following from them? If we can, name the inference rule being used: For all x_16, x_16 will not go running.
 From the fact that for all x_16, x_16 will go running if and only if x_16 will take a plane we can infer that for all x_16, if x_16 takes a plane, then x_16 is running via universal biconditional elimination. From the fact that there is at least one x_16 for which x_16 will play squash we can infer that there is at least one x_16 for which x_16 will play squash or x_16 will drink water via existential addition. From the fact that for all x_16, if x_16 plays squash, then x_16 is taking a plane, that for all x_16, if x_16 drinks water, then x_16 is taking a plane, and that there is at least one x_16 for which x_16 will play squash or x_16 will drink water we can infer that there is at least one x_16 for which x_16 will take a plane via existential disjunction elimination. Finally, from the fact that for all x_16, if x_16 takes a plane, then x_16 is running, and that there is at least one x_16 for which x_16 will take a plane we can infer that there is at least one x_16 for which x_16 will go running via existential modus ponens, which contradicts that For all x_16, x_16 will not go running. Therefore, the answer is no.