Consider the following premises. For all x_13, x_13 is a sailor if and only if x_13 will climb a mountain. There is at least one x_13 for which if x_13 were a sailor, then x_13 is running. For all x_13, if x_13 climbs a mountain, then x_13 is working. For all x_13, x_13 will go running if and only if x_13 is a sailor. For all x_13, x_13 will not work. Can we infer the following from them? There is at least one x_13 for which x_13 will not go running.
 From the fact that for all x_13, x_13 will go running if and only if x_13 is a sailor we can infer that for all x_13, if x_13 goes running, then x_13 is a sailor. From the fact that for all x_13, if x_13 climbs a mountain, then x_13 is working, and that for all x_13, x_13 will not work we can infer that for all x_13, x_13 will not climb a mountain. From the fact that for all x_13, x_13 is a sailor if and only if x_13 will climb a mountain, and that for all x_13, x_13 will not climb a mountain we can infer that for all x_13, x_13 is not a sailor. From the fact that there is at least one x_13 for which if x_13 were a sailor, then x_13 is running, and that for all x_13, if x_13 goes running, then x_13 is a sailor we can infer that there is at least one x_13 for which x_13 is a sailor if and only if x_13 will go running. Finally, from the fact that there is at least one x_13 for which x_13 is a sailor if and only if x_13 will go running, and that for all x_13, x_13 is not a sailor we can infer that there is at least one x_13 for which x_13 will not go running. Therefore, the answer is yes.