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_6, x_6 will go running if and only if x_6 is a taxi driver. For all x_6, x_6 is a taxi driver. There is at least one x_6 for which if x_6 were a mechanic, then x_6 is running.
For all x_6, if x_6 goes running, then x_6 is a taxi driver can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were a taxi driver, then x_6 is running can be inferred via the universal biconditional elimination rule.