Consider the following premises. For all x_11, x_11 is a police officer if and only if x_11 will work. For all x_11, if x_11 were a doctor, then x_11 is running. For all x_11, x_11 is happy or x_11 is a police officer. For all x_11, if x_11 were happy, then x_11 is running. For all x_11, if x_11 works, then x_11 is a doctor. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_11 for which x_11 will not go running.
 From the fact that for all x_11, x_11 is a police officer if and only if x_11 will work we can infer that for all x_11, if x_11 were a police officer, then x_11 is working via universal biconditional elimination. From the fact that for all x_11, if x_11 works, then x_11 is a doctor, and that for all x_11, if x_11 were a doctor, then x_11 is running we can infer that for all x_11, if x_11 works, then x_11 is running via universal transitivity. From the fact that for all x_11, if x_11 were a police officer, then x_11 is working, and that for all x_11, if x_11 works, then x_11 is running we can infer that for all x_11, if x_11 were a police officer, then x_11 is running via universal transitivity. Finally, from the fact that for all x_11, if x_11 were happy, then x_11 is running, that for all x_11, if x_11 were a police officer, then x_11 is running, and that for all x_11, x_11 is happy or x_11 is a police officer we can infer that for all x_11, x_11 will go running via universal disjunction elimination, which contradicts that There is at least one x_11 for which x_11 will not go running. Therefore, the answer is no.