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 -> q. p_8 -> q_1. q -> p_8. q_1 -> p_8. ~q.
~p_8 can be inferred via the modus tollens rule. q -> q_1 can be inferred via the transitivity rule. q_1 -> q can be inferred via the transitivity rule. p_8 <-> q can be inferred via the biconditional introduction rule. p_8 <-> q_1 can be inferred via the biconditional introduction rule. q <-> p_8 can be inferred via the biconditional introduction rule. q_1 <-> p_8 can be inferred via the biconditional introduction rule.