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: q -> q_1. p_8 <-> q_8. q_1 <-> q_8. ~p_8.
p_8 -> q_8 can be inferred via the biconditional elimination rule. q_1 -> q_8 can be inferred via the biconditional elimination rule. q_8 -> p_8 can be inferred via the biconditional elimination rule. q_8 -> q_1 can be inferred via the biconditional elimination rule. ~q_8 can be inferred via the biconditional elimination rule.