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: If it snows, then Joseph is driving a car. If Joseph drives a car, then it is snowing. It is not snowing. Joseph is driving a car if and only if David is a scientist.
Joseph is not driving a car can be inferred via the modus tollens rule. It is snowing if and only if Joseph is driving a car can be inferred via the biconditional introduction rule. Joseph is driving a car if and only if it is snowing can be inferred via the biconditional introduction rule. If Joseph drives a car, then David is a scientist can be inferred via the biconditional elimination rule. If David were a scientist, then Joseph is driving a car can be inferred via the biconditional elimination rule.