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 <-> p_11. r. q. p_11 -> ~r.
~p_11 can be inferred via the modus tollens rule. r and q can be inferred via the conjunction rule. q and r can be inferred via the conjunction rule. p -> p_11 can be inferred via the biconditional elimination rule. p_11 -> p can be inferred via the biconditional elimination rule.