Consider the following premises. For all x, if x plays a game, then x is a poet. For all x, x is a poet if and only if x will play a game. Can we infer the following from them? If we can, name the inference rule being used: If Richard were a poet, then Richard is playing a game.
 From the fact that for all x, x is a poet if and only if x will play a game we can infer that for all x, if x were a poet, then x is playing a game via universal biconditional elimination. From the fact that for all x, if x plays a game, then x is a poet, and that for all x, if x were a poet, then x is playing a game we can infer that for all x, x will play a game if and only if x is a poet via universal biconditional introduction. From the fact that for all x, x will play a game if and only if x is a poet we can infer that Richard is playing a game if and only if Richard is a poet via universal instantiation. Finally, from the fact that Richard is playing a game if and only if Richard is a poet we can infer that if Richard were a poet, then Richard is playing a game via biconditional elimination. Therefore, the answer is yes.