Consider the following premises. For all x_11, x_11 is sad or x_11 will write a letter. For all x_11, if x_11 takes a plane, then x_11 is a server. For all x_11, x_11 is not sad. There is at least one x_11 for which x_11 will take a plane. Can we infer the following from them? Some servers will write a letter.
 From the fact that for all x_11, x_11 is sad or x_11 will write a letter, and that for all x_11, x_11 is not sad we can infer that for all x_11, x_11 will write a letter. From the fact that for all x_11, if x_11 takes a plane, then x_11 is a server, and that there is at least one x_11 for which x_11 will take a plane we can infer that there is at least one x_11 for which x_11 is a server. Finally, from the fact that there is at least one x_11 for which x_11 is a server, and that for all x_11, x_11 will write a letter we can infer that some servers will write a letter. Therefore, the answer is yes.