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 overcast. John is driving a car if and only if Sarah is playing squash. For all x_16, x_16 will not drive a car.
If John drives a car, then Sarah is playing squash can be inferred via the biconditional elimination rule. If Sarah plays squash, then John is driving a car can be inferred via the biconditional elimination rule.