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_6. t -> r_6. q -> t. p_4 <-> p_11. p_11 -> q.
~t can be inferred via the modus tollens rule. q -> r_6 can be inferred via the transitivity rule. p_11 -> t can be inferred via the transitivity rule. p_4 -> p_11 can be inferred via the biconditional elimination rule. p_11 -> p_4 can be inferred via the biconditional elimination rule.