Consider the following premises. For all x_4, x_4 will not play squash or x_4 is a sailor. For all x_4, x_4 will play squash or x_4 is a writer. For all x_4, if x_4 writes a letter, then x_4 is climbing a mountain. For all x_4, if x_4 were a sailor, then x_4 is climbing a mountain. For all x_4, x_4 is not a writer or x_4 will write a letter. Can we infer the following from them? There is at least one x_4 for which x_4 will not climb a mountain.
 From the fact that for all x_4, x_4 will play squash or x_4 is a writer, and that for all x_4, x_4 will not play squash or x_4 is a sailor we can infer that for all x_4, x_4 is a writer or x_4 is a sailor. From the fact that for all x_4, x_4 is a writer or x_4 is a sailor, and that for all x_4, x_4 is not a writer or x_4 will write a letter we can infer that for all x_4, x_4 is a sailor or x_4 will write a letter. Finally, from the fact that for all x_4, if x_4 were a sailor, then x_4 is climbing a mountain, that for all x_4, if x_4 writes a letter, then x_4 is climbing a mountain, and that for all x_4, x_4 is a sailor or x_4 will write a letter we can infer that for all x_4, x_4 will climb a mountain, which contradicts that There is at least one x_4 for which x_4 will not climb a mountain. Therefore, the answer is no.