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: If Barbara were rich, then Michael is a server. If Michael were a server, then Barbara is a writer. Barbara is rich if and only if it is cloudy.
If Barbara were rich, then Barbara is a writer can be inferred via the transitivity rule. If Barbara were rich, then it is cloudy can be inferred via the biconditional elimination rule. If it is cloudy, then Barbara is rich can be inferred via the biconditional elimination rule.