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_8. p_8 <-> u. u <-> t_1.
p_8 -> u can be inferred via the biconditional elimination rule. u -> t_1 can be inferred via the biconditional elimination rule. u -> p_8 can be inferred via the biconditional elimination rule. t_1 -> u can be inferred via the biconditional elimination rule. ~u can be inferred via the biconditional elimination rule.