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