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: For all x_7, x_7 will drive a car if and only if x_7 will sleep. Mary is not driving a car. It is snowing if and only if Mary is sleeping.
If it snows, then Mary is sleeping can be inferred via the biconditional elimination rule. If Mary sleeps, then it is snowing can be inferred via the biconditional elimination rule. For all x_7, if x_7 drives a car, then x_7 is sleeping can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 sleeps, then x_7 is driving a car can be inferred via the universal biconditional elimination rule.