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_6 <-> t. t <-> q. p_6 -> w. ~w.
~p_6 can be inferred via the modus tollens rule. p_6 -> t can be inferred via the biconditional elimination rule. t -> q can be inferred via the biconditional elimination rule. t -> p_6 can be inferred via the biconditional elimination rule. q -> t can be inferred via the biconditional elimination rule.