Consider the following premises. For all x_16, x_16 will play tennis if and only if x_16 is a lawyer. There is at least one x_16 for which x_16 is a sailor. For all x_16, if x_16 were a police officer, then x_16 is not a sailor. For all x_16, if x_16 plays tennis, then x_16 is a police officer. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_16 for which x_16 is not a lawyer.
 From the fact that for all x_16, x_16 will play tennis if and only if x_16 is a lawyer we can infer that for all x_16, if x_16 were a lawyer, then x_16 is playing tennis via universal biconditional elimination. From the fact that for all x_16, if x_16 were a lawyer, then x_16 is playing tennis, and that for all x_16, if x_16 plays tennis, then x_16 is a police officer we can infer that for all x_16, if x_16 were a lawyer, then x_16 is a police officer via universal transitivity. From the fact that for all x_16, if x_16 were a police officer, then x_16 is not a sailor, and that there is at least one x_16 for which x_16 is a sailor we can infer that there is at least one x_16 for which x_16 is not a police officer via existential modus tollens. Finally, from the fact that for all x_16, if x_16 were a lawyer, then x_16 is a police officer, and that there is at least one x_16 for which x_16 is not a police officer we can infer that there is at least one x_16 for which x_16 is not a lawyer via existential modus tollens. Therefore, the answer is yes.