Consider the following premises. If John were a writer, then Karen is playing a game. If Charles plays tennis, then Karen is playing a game. If Charles plays tennis, then John is a writer. If Karen plays a game, then Charles is playing tennis. Can we infer the following from them? If is not true that Karen is playing a game if and only if Charles is playing tennis.
 From the fact that if Charles plays tennis, then John is a writer, and that if John were a writer, then Karen is playing a game we can infer that if Charles plays tennis, then Karen is playing a game. From the fact that if Charles plays tennis, then Karen is playing a game, and that if Karen plays a game, then Charles is playing tennis we can infer that Charles is playing tennis if and only if Karen is playing a game. From the fact that Charles is playing tennis if and only if Karen is playing a game we can infer that if Karen plays a game, then Charles is playing tennis. Finally, from the fact that if Karen plays a game, then Charles is playing tennis, and that if Charles plays tennis, then Karen is playing a game we can infer that Karen is playing a game if and only if Charles is playing tennis, which contradicts that If is not true that Karen is playing a game if and only if Charles is playing tennis. Therefore, the answer is no.