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_8, x_8 is a cashier if and only if x_8 is a lawyer. For all x_8, x_8 is a cashier or x_8 is not a lawyer. There is at least one x_8 for which x_8 is not a lawyer.
For all x_8, if x_8 were a lawyer, then x_8 is a cashier can be inferred via the universal rewriting rule. For all x_8, if x_8 were a cashier, then x_8 is a lawyer can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a lawyer, then x_8 is a cashier can be inferred via the universal biconditional elimination rule. There is at least one x_8 for which x_8 is not a cashier can be inferred via the existential biconditional elimination rule.