Consider the following premises. For all x_8, x_8 will take a plane if and only if x_8 will climb a mountain. For all x_8, if x_8 climbs a mountain, then x_8 is not playing a game. For all x_8, if x_8 climbs a mountain, then x_8 is taking a plane. For all x_8, x_8 will play a game. Can we infer the following from them? There is at least one x_8 for which x_8 will take a plane.
 From the fact that for all x_8, x_8 will take a plane if and only if x_8 will climb a mountain we can infer that for all x_8, if x_8 takes a plane, then x_8 is climbing a mountain. From the fact that for all x_8, if x_8 climbs a mountain, then x_8 is not playing a game, and that for all x_8, x_8 will play a game we can infer that for all x_8, x_8 will not climb a mountain. From the fact that for all x_8, if x_8 climbs a mountain, then x_8 is taking a plane, and that for all x_8, if x_8 takes a plane, then x_8 is climbing a mountain we can infer that for all x_8, x_8 will climb a mountain if and only if x_8 will take a plane. Finally, from the fact that for all x_8, x_8 will climb a mountain if and only if x_8 will take a plane, and that for all x_8, x_8 will not climb a mountain we can infer that for all x_8, x_8 will not take a plane, which contradicts that There is at least one x_8 for which x_8 will take a plane. Therefore, the answer is no.