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_3, if x_3 were a taxi driver, then x_3 is an office clerk. For all x_3, x_3 is an office clerk if and only if x_3 will go running. For all x_3, if x_3 were an office clerk, then x_3 is a taxi driver. If Joseph were a soldier, then Jennifer is a taxi driver. For all x_3, x_3 will not go running.
For all x_3, x_3 is a taxi driver if and only if x_3 is an office clerk can be inferred via the universal biconditional introduction rule. For all x_3, x_3 is an office clerk if and only if x_3 is a taxi driver can be inferred via the universal biconditional introduction rule. For all x_3, if x_3 were an office clerk, then x_3 is running can be inferred via the universal biconditional elimination rule. For all x_3, if x_3 goes running, then x_3 is an office clerk can be inferred via the universal biconditional elimination rule. For all x_3, x_3 is not an office clerk can be inferred via the universal biconditional elimination rule.