What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: It is snowing if and only if it is raining. It is windy. If it is windy, then Barbara is reading a book. It is not raining.
Barbara is reading a book can be inferred via the modus ponens rule. It is windy and it is not raining can be inferred via the conjunction rule. It is not raining and it is windy can be inferred via the conjunction rule. If it snows, then it is raining can be inferred via the biconditional elimination rule. If it rains, then it is snowing can be inferred via the biconditional elimination rule. It is not snowing can be inferred via the biconditional elimination rule.