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, x is a taxi driver if and only if x will drink water.
For all x, if x were a taxi driver, then x is drinking water can be inferred via the universal biconditional elimination rule. For all x, if x drinks water, then x is a taxi driver can be inferred via the universal biconditional elimination rule.