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, z is poor if and only if z will take a plane. For all z, z will take a plane if and only if z is a police officer.
For all z, if z were poor, then z is taking a plane can be inferred via the universal biconditional elimination rule. For all z, if z takes a plane, then z is a police officer can be inferred via the universal biconditional elimination rule. For all z, if z takes a plane, then z is poor can be inferred via the universal biconditional elimination rule. For all z, if z were a police officer, then z is taking a plane can be inferred via the universal biconditional elimination rule.