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 is not a cashier. There is at least one x_7 for which x_7 will drive a car if and only if x_7 is a cashier. For all x_7, x_7 will drive a car or x_7 will drink water.
There is at least one x_7 for which if x_7 drives a car, then x_7 is a cashier can be inferred via the existential biconditional elimination rule. There is at least one x_7 for which if x_7 were a cashier, then x_7 is driving a car can be inferred via the existential biconditional elimination rule. There is at least one x_7 for which x_7 will not drive a car can be inferred via the existential biconditional elimination rule.