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 Barbara is playing tennis. For all x_2, if x_2 plays tennis, then x_2 is excited.
If Barbara were excited, then Barbara is playing tennis can be inferred via the biconditional elimination rule. If Barbara plays tennis, then Barbara is excited can be inferred via the biconditional elimination rule.