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_2 -> q. r <-> p_1. ~q. ~p_1.
~p_2 can be inferred via the modus tollens rule. ~q and ~p_1 can be inferred via the conjunction rule. ~p_1 and ~q can be inferred via the conjunction rule. r -> p_1 can be inferred via the biconditional elimination rule. p_1 -> r can be inferred via the biconditional elimination rule. ~r can be inferred via the biconditional elimination rule.