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 -> q. u_1 <-> q. u_1 -> w.
u_1 -> q can be inferred via the transitivity rule. u_1 -> q can be inferred via the biconditional elimination rule. q -> u_1 can be inferred via the biconditional elimination rule.