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_11, x_11 is a cashier if and only if x_11 is an office clerk. For all x_11, if x_11 were rich, then x_11 is an office clerk. There is at least one x_11 for which if x_11 were a cashier, then x_11 is rich.
There is at least one x_11 for which if x_11 were a cashier, then x_11 is an office clerk can be inferred via the existential transitivity rule. For all x_11, if x_11 were a cashier, then x_11 is an office clerk can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 were an office clerk, then x_11 is a cashier can be inferred via the universal biconditional elimination rule.