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, x_6 is a nurse. For all x_6, x_6 is a cashier if and only if x_6 is curious. For all x_6, if x_6 were an artist, then x_6 is not a nurse. For all x_6, x_6 is an artist if and only if x_6 is a cashier.
For all x_6, x_6 is not an artist can be inferred via the universal modus tollens rule. For all x_6, if x_6 were a cashier, then x_6 is curious can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were an artist, then x_6 is a cashier can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were curious, then x_6 is a cashier can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were a cashier, then x_6 is an artist can be inferred via the universal biconditional elimination rule.