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: u -> q. w -> u. q -> w. u -> w.
u -> w can be inferred via the transitivity rule. w -> q can be inferred via the transitivity rule. q -> u can be inferred via the transitivity rule. w <-> u can be inferred via the biconditional introduction rule. u <-> w can be inferred via the biconditional introduction rule.