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_2, x_2 is a bartender if and only if x_2 is a server. Richard is not a server.
For all x_2, if x_2 were a bartender, then x_2 is a server can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 were a server, then x_2 is a bartender can be inferred via the universal biconditional elimination rule.