Consider the following premises. John is a writer. Thomas is climbing a mountain if and only if it is snowing. John is a writer if and only if it is snowing. Can we infer the following from them? It is not snowing.
 From the fact that Thomas is climbing a mountain if and only if it is snowing we can infer that if Thomas climbs a mountain, then it is snowing. From the fact that John is a writer we can infer that John is a writer or Thomas is climbing a mountain. From the fact that John is a writer if and only if it is snowing we can infer that if John were a writer, then it is snowing. Finally, from the fact that if John were a writer, then it is snowing, that if Thomas climbs a mountain, then it is snowing, and that John is a writer or Thomas is climbing a mountain we can infer that it is snowing, which contradicts that It is not snowing. Therefore, the answer is no.