Consider the following premises. For all x_11, x_11 is fast if and only if x_11 will drink water. For all x_11, x_11 is not fast. For all x_11, x_11 will sleep if and only if x_11 will drink water. For all x_11, if x_11 were a sailor, then x_11 is cooking. For all x_11, if x_11 cooks, then x_11 is sleeping. Can we infer the following from them? There is at least one x_11 for which x_11 is a sailor.
 From the fact that for all x_11, x_11 is fast if and only if x_11 will drink water, and that for all x_11, x_11 is not fast we can infer that for all x_11, x_11 will not drink water. From the fact that for all x_11, x_11 will sleep if and only if x_11 will drink water, and that for all x_11, x_11 will not drink water we can infer that for all x_11, x_11 will not sleep. From the fact that for all x_11, if x_11 cooks, then x_11 is sleeping, and that for all x_11, x_11 will not sleep we can infer that for all x_11, x_11 will not cook. Finally, from the fact that for all x_11, if x_11 were a sailor, then x_11 is cooking, and that for all x_11, x_11 will not cook we can infer that for all x_11, x_11 is not a sailor, which contradicts that There is at least one x_11 for which x_11 is a sailor. Therefore, the answer is no.