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 -> p_1. w_1 -> p_1. q -> w_1. p_1 -> q.
w_1 -> q can be inferred via the transitivity rule. q -> p_1 can be inferred via the transitivity rule. p_1 -> w_1 can be inferred via the transitivity rule. q <-> p_1 can be inferred via the biconditional introduction rule. p_1 <-> q can be inferred via the biconditional introduction rule.