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 will drink water if and only if x_5 is a taxi driver. For all x_5, x_5 is a server if and only if x_5 is a taxi driver. For all x_5, if x_5 drinks water, then x_5 is taking a plane. For all x_5, x_5 will not take a plane.
For all x_5, x_5 will not drink water can be inferred via the universal modus tollens rule. For all x_5, if x_5 drinks water, 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 server, 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 drinking water 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 server can be inferred via the universal biconditional elimination rule.