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 x_5, x_5 is a police officer if and only if x_5 is a taxi driver. For all x_5, x_5 will sleep. For all x_5, if x_5 sleeps, then x_5 is a taxi driver.
For all x_5, x_5 is a taxi driver can be inferred via the universal modus ponens rule. For all x_5, if x_5 were a police officer, then x_5 is a taxi driver can be inferred via the universal biconditional elimination rule. For all x_5, if x_5 were a taxi driver, then x_5 is a police officer can be inferred via the universal biconditional elimination rule.