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: Michael is a nurse if and only if Michael is a doctor. For all y, y is sad. Michael is not a doctor.
If Michael were a nurse, then Michael is a doctor can be inferred via the biconditional elimination rule. If Michael were a doctor, then Michael is a nurse can be inferred via the biconditional elimination rule. Michael is not a nurse can be inferred via the biconditional elimination rule.