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 cooks, then x_6 is a server. For all x_6, if x_6 were a server, then x_6 is a soldier. For all x_6, if x_6 were a nurse, then x_6 is a bartender. There is at least one x_6 for which if x_6 were a soldier, then x_6 is a nurse.
For all x_6, if x_6 cooks, then x_6 is a soldier can be inferred via the universal transitivity rule. There is at least one x_6 for which if x_6 were a soldier, then x_6 is a bartender can be inferred via the existential transitivity rule. There is at least one x_6 for which if x_6 were a server, then x_6 is a nurse can be inferred via the existential transitivity rule.