Consider the following premises. For all x_8, if x_8 were happy, then x_8 is running. Robert is happy. For all x_8, if x_8 goes running, then x_8 is happy. Can we infer the following from them? If we can, name the inference rule being used: Robert is running.
 From the fact that for all x_8, if x_8 were happy, then x_8 is running, and that for all x_8, if x_8 goes running, then x_8 is happy we can infer that for all x_8, x_8 is happy if and only if x_8 will go running via universal biconditional introduction. From the fact that for all x_8, x_8 is happy if and only if x_8 will go running we can infer that Robert is happy if and only if Robert is running via universal instantiation. From the fact that Robert is happy if and only if Robert is running we can infer that if Robert were happy, then Robert is running via biconditional elimination. Finally, from the fact that if Robert were happy, then Robert is running, and that Robert is happy we can infer that Robert is running via modus ponens. Therefore, the answer is yes.