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_6, if x_6 were an artist, then x_6 is playing tennis. There is at least one x_6 for which if x_6 plays tennis, then x_6 is a server. For all x_6, x_6 is a server if and only if x_6 will drive a car.
There is at least one x_6 for which if x_6 were an artist, then x_6 is a server can be inferred via the existential transitivity rule. For all x_6, if x_6 were a server, then x_6 is driving a car can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 drives a car, then x_6 is a server can be inferred via the universal biconditional elimination rule.