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: There is at least one z for which if z were a police officer, then z is playing squash. For all z, if z were poor, then z is a police officer. For all z, z is poor if and only if z will play squash. For all z, z is not a police officer.
For all z, z is not poor can be inferred via the universal modus tollens rule. There is at least one z for which if z were poor, then z is playing squash can be inferred via the existential transitivity rule. For all z, if z were poor, then z is playing squash can be inferred via the universal biconditional elimination rule. For all z, if z plays squash, then z is poor can be inferred via the universal biconditional elimination rule.