Consider the following premises. For all x_11, if x_11 writes a letter, then x_11 is climbing a mountain. For all x_11, x_11 is a musician. For all x_11, if x_11 were a sailor, then x_11 is climbing a mountain. There is at least one x_11 for which x_11 will write a letter or x_11 is a sailor. Can we infer the following from them? For all x_11, x_11 will not climb a mountain.
 From the fact that for all x_11, if x_11 writes a letter, then x_11 is climbing a mountain, that for all x_11, if x_11 were a sailor, then x_11 is climbing a mountain, and that there is at least one x_11 for which x_11 will write a letter or x_11 is a sailor we can infer that there is at least one x_11 for which x_11 will climb a mountain. From the fact that for all x_11, x_11 is a musician, and that there is at least one x_11 for which x_11 will climb a mountain we can infer that some musicians will climb a mountain. Finally, from the fact that some musicians will climb a mountain we can infer that there is at least one x_11 for which x_11 is a musician, which contradicts that For all x_11, x_11 will not climb a mountain. Therefore, the answer is no.