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: Barbara is excited if and only if Elisabeth is drinking water. For all z, z will not drink water.
If Barbara were excited, then Elisabeth is drinking water can be inferred via the biconditional elimination rule. If Elisabeth drinks water, then Barbara is excited can be inferred via the biconditional elimination rule.