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 <-> w_1. u_1 or p_1. ~u. w_1 <-> u_1.
u -> w_1 can be inferred via the biconditional elimination rule. w_1 -> u_1 can be inferred via the biconditional elimination rule. w_1 -> u can be inferred via the biconditional elimination rule. u_1 -> w_1 can be inferred via the biconditional elimination rule. ~w_1 can be inferred via the biconditional elimination rule.