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: w or r_1. w <-> q_8. q_8 <-> r_1.
w -> q_8 can be inferred via the biconditional elimination rule. q_8 -> r_1 can be inferred via the biconditional elimination rule. q_8 -> w can be inferred via the biconditional elimination rule. r_1 -> q_8 can be inferred via the biconditional elimination rule.