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_3, z_3 is not a taxi driver. There is at least one z_3 for which z_3 is a taxi driver if and only if z_3 will play squash. For all z_3, if z_3 plays squash, then z_3 is a taxi driver.
For all z_3, z_3 will not play squash can be inferred via the universal modus tollens rule. There is at least one z_3 for which if z_3 were a taxi driver, then z_3 is playing squash can be inferred via the existential biconditional elimination rule. There is at least one z_3 for which if z_3 plays squash, then z_3 is a taxi driver can be inferred via the existential biconditional elimination rule. There is at least one z_3 for which z_3 will not play squash can be inferred via the existential biconditional elimination rule.