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 curious, then x_6 is fast. There is at least one x_6 for which if x_6 were fast, then x_6 is a cashier. For all x_6, if x_6 were a cashier, then x_6 is taking a plane. For all x_6, if x_6 takes a plane, then x_6 is curious.
For all x_6, if x_6 were a cashier, then x_6 is curious can be inferred via the universal transitivity rule. For all x_6, if x_6 takes a plane, then x_6 is fast can be inferred via the universal transitivity rule. There is at least one x_6 for which if x_6 were fast, then x_6 is taking a plane can be inferred via the existential transitivity rule. There is at least one x_6 for which if x_6 were curious, then x_6 is a cashier can be inferred via the existential transitivity rule.