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 a nurse. For all x_7, if x_7 were a nurse, then x_7 is a lawyer. For all x_7, x_7 is not a taxi driver. For all x_7, x_7 is a taxi driver or x_7 is a server.
For all x_7, x_7 is a lawyer can be inferred via the universal modus ponens rule. For all x_7, x_7 is a server can be inferred via the universal disjunctive syllogism rule.