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: Barbara is a lawyer if and only if Michael is a bartender. Michael is a bartender. It is sunny or Richard is rich. It is not sunny.
Richard is rich can be inferred via the disjunctive syllogism rule. Michael is a bartender and it is not sunny can be inferred via the conjunction rule. It is not sunny and Michael is a bartender can be inferred via the conjunction rule. If Barbara were a lawyer, then Michael is a bartender can be inferred via the biconditional elimination rule. If Michael were a bartender, then Barbara is a lawyer can be inferred via the biconditional elimination rule.