Consider the following premises. Richard is a politician. For all x_14, x_14 is a police officer if and only if x_14 is a politician. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_14 for which x_14 is a police officer or x_14 is a writer.
 From the fact that Richard is a politician we can infer that there is at least one x_14 for which x_14 is a politician via existential generalization. From the fact that for all x_14, x_14 is a police officer if and only if x_14 is a politician we can infer that for all x_14, if x_14 were a politician, then x_14 is a police officer via universal biconditional elimination. From the fact that for all x_14, if x_14 were a politician, then x_14 is a police officer, and that there is at least one x_14 for which x_14 is a politician we can infer that there is at least one x_14 for which x_14 is a police officer via existential modus ponens. Finally, from the fact that there is at least one x_14 for which x_14 is a police officer we can infer that there is at least one x_14 for which x_14 is a police officer or x_14 is a writer via existential addition. Therefore, the answer is yes.