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: There is at least one x_12 for which if x_12 were a sailor, then x_12 is driving a car. For all x_12, if x_12 drives a car, then x_12 is a sailor. For all x_12, if x_12 were a sailor, then x_12 is playing a game. For all x_12, if x_12 plays a game, then x_12 is driving a car.
For all x_12, if x_12 drives a car, then x_12 is playing a game can be inferred via the universal transitivity rule. For all x_12, if x_12 were a sailor, then x_12 is driving a car can be inferred via the universal transitivity rule. For all x_12, if x_12 plays a game, then x_12 is a sailor can be inferred via the universal transitivity rule. There is at least one x_12 for which x_12 is a sailor if and only if x_12 will drive a car can be inferred via the existential biconditional introduction rule. There is at least one x_12 for which x_12 will drive a car if and only if x_12 is a sailor can be inferred via the existential biconditional introduction rule.