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 z_2, z_2 is a cashier if and only if z_2 will go running. For all z_2, z_2 will go running if and only if z_2 is a cashier.
For all z_2, if z_2 were a cashier, then z_2 is running can be inferred via the universal biconditional elimination rule. For all z_2, if z_2 goes running, then z_2 is a cashier can be inferred via the universal biconditional elimination rule. For all z_2, if z_2 goes running, then z_2 is a cashier can be inferred via the universal biconditional elimination rule. For all z_2, if z_2 were a cashier, then z_2 is running can be inferred via the universal biconditional elimination rule.