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: p_3 -> q. q -> p_3. q.
p_3 can be inferred via the modus ponens rule. p_3 <-> q can be inferred via the biconditional introduction rule. q <-> p_3 can be inferred via the biconditional introduction rule.