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: r. s <-> p_11. q_1. p_11 -> ~r.
~p_11 can be inferred via the modus tollens rule. r and q_1 can be inferred via the conjunction rule. q_1 and r can be inferred via the conjunction rule. s -> p_11 can be inferred via the biconditional elimination rule. p_11 -> s can be inferred via the biconditional elimination rule.