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_2, z_2 is a poet. Elisabeth is cooking if and only if Mary is a doctor. Mary is not a doctor.
If Elisabeth cooks, then Mary is a doctor can be inferred via the biconditional elimination rule. If Mary were a doctor, then Elisabeth is cooking can be inferred via the biconditional elimination rule. Elisabeth is not cooking can be inferred via the biconditional elimination rule.