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_1 -> w_1. w_3 <-> w_1. w_3 -> u_1.
w_3 -> w_1 can be inferred via the transitivity rule. w_3 -> w_1 can be inferred via the biconditional elimination rule. w_1 -> w_3 can be inferred via the biconditional elimination rule.