Consider the following premises. If it snows, then Patricia is a politician. If Patricia were a politician, then it is snowing. If Elisabeth were an artist, then it is snowing. Patricia is a politician or Elisabeth is an artist. Can we infer the following from them? If we can, name the inference rule being used: It is snowing.
 From the fact that if Patricia were a politician, then it is snowing, and that if it snows, then Patricia is a politician we can infer that Patricia is a politician if and only if it is snowing via biconditional introduction. From the fact that Patricia is a politician if and only if it is snowing we can infer that if Patricia were a politician, then it is snowing via biconditional elimination. Finally, from the fact that if Patricia were a politician, then it is snowing, that if Elisabeth were an artist, then it is snowing, and that Patricia is a politician or Elisabeth is an artist we can infer that it is snowing via disjunction elimination. Therefore, the answer is yes.