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_1, if x_1 were a politician, then x_1 is a nurse. For all x_1, if x_1 were a nurse, then x_1 is a politician.
For all x_1, x_1 is a politician if and only if x_1 is a nurse can be inferred via the universal biconditional introduction rule. For all x_1, x_1 is a nurse if and only if x_1 is a politician can be inferred via the universal biconditional introduction rule.