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: u. p_3 -> ~u. p_3 <-> q_7.
~p_3 can be inferred via the modus tollens rule. p_3 -> q_7 can be inferred via the biconditional elimination rule. q_7 -> p_3 can be inferred via the biconditional elimination rule.