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_8 -> p_1. p_1 -> q_8. q_8 -> p_1.
q_8 <-> p_1 can be inferred via the biconditional introduction rule. p_1 <-> q_8 can be inferred via the biconditional introduction rule. p_1 <-> q_8 can be inferred via the biconditional introduction rule. q_8 <-> p_1 can be inferred via the biconditional introduction rule.