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: w or ~t. t <-> q_9.
t -> w can be inferred via the rewriting rule. t -> q_9 can be inferred via the biconditional elimination rule. q_9 -> t can be inferred via the biconditional elimination rule.