Consider the following premises. For all x_6, x_6 is sad. For all x_6, x_6 is not a taxi driver or x_6 will climb a mountain. For all x_6, x_6 is a taxi driver or x_6 is rich. For all x_6, x_6 is not rich. Can we infer the following from them? There is at least one x_6 for which either x_6 is sad or x_6 will climb a mountain are not true.
 From the fact that for all x_6, x_6 is a taxi driver or x_6 is rich, and that for all x_6, x_6 is not a taxi driver or x_6 will climb a mountain we can infer that for all x_6, x_6 is rich or x_6 will climb a mountain. From the fact that for all x_6, x_6 is rich or x_6 will climb a mountain, and that for all x_6, x_6 is not rich we can infer that for all x_6, x_6 will climb a mountain. Finally, from the fact that for all x_6, x_6 is sad, and that for all x_6, x_6 will climb a mountain we can infer that for all x_6, x_6 is sad and x_6 will climb a mountain, which contradicts that There is at least one x_6 for which either x_6 is sad or x_6 will climb a mountain are not true. Therefore, the answer is no.