Consider the following premises. Robert is playing a game if and only if Richard is a nurse. John is fast or Robert is not playing a game. John is not fast. Can we infer the following from them? Richard is a nurse.
 From the fact that John is fast or Robert is not playing a game we can infer that if Robert plays a game, then John is fast. From the fact that if Robert plays a game, then John is fast, and that John is not fast we can infer that Robert is not playing a game. Finally, from the fact that Robert is playing a game if and only if Richard is a nurse, and that Robert is not playing a game we can infer that Richard is not a nurse, which contradicts that Richard is a nurse. Therefore, the answer is no.