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_17, if x_17 were an astronaut, then x_17 is a server. Richard is a server if and only if Barbara is drinking water. If Barbara drinks water, then Richard is an astronaut.
If Richard were a server, then Barbara is drinking water can be inferred via the biconditional elimination rule. If Barbara drinks water, then Richard is a server can be inferred via the biconditional elimination rule.