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_1 or ~p_9. r_1 <-> t. p_9 or ~r_1. ~t.
p_9 -> r_1 can be inferred via the rewriting rule. r_1 -> p_9 can be inferred via the rewriting rule. r_1 -> t can be inferred via the biconditional elimination rule. t -> r_1 can be inferred via the biconditional elimination rule. ~r_1 can be inferred via the biconditional elimination rule.