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: u -> p_8. q_8 -> u. p_8 -> u. p_8 -> q_8.
u -> q_8 can be inferred via the transitivity rule. q_8 -> p_8 can be inferred via the transitivity rule. p_8 -> u can be inferred via the transitivity rule. u <-> p_8 can be inferred via the biconditional introduction rule. p_8 <-> u can be inferred via the biconditional introduction rule.