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 poor, then z is cooking. For all z, z will cook or z is not poor. For all z, if z cooks, then z is poor.
For all z, if z were poor, then z is cooking can be inferred via the universal rewriting rule. For all z, z is poor if and only if z will cook can be inferred via the universal biconditional introduction rule. For all z, z will cook if and only if z is poor can be inferred via the universal biconditional introduction rule.