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, if z were a politician, then z is rich. For all z, z is not a janitor. For all z, if z were a janitor, then z is rich. For all z, if z were rich, then z is a janitor. For all z, if z were rich, then z is a politician.
For all z, z is not rich can be inferred via the universal modus tollens rule. For all z, if z were a politician, then z is a janitor can be inferred via the universal transitivity rule. For all z, if z were a janitor, then z is a politician can be inferred via the universal transitivity rule. For all z, z is a politician if and only if z is rich can be inferred via the universal biconditional introduction rule. For all z, z is a janitor if and only if z is rich can be inferred via the universal biconditional introduction rule. For all z, z is rich if and only if z is a janitor can be inferred via the universal biconditional introduction rule. For all z, z is rich if and only if z is a politician can be inferred via the universal biconditional introduction rule.