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_9 <-> w. ~p_9. w <-> t.
p_9 -> w can be inferred via the biconditional elimination rule. w -> t can be inferred via the biconditional elimination rule. w -> p_9 can be inferred via the biconditional elimination rule. t -> w can be inferred via the biconditional elimination rule. ~w can be inferred via the biconditional elimination rule.