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: ~q. q or q_13. u <-> w. r -> u. ~w.
q_13 can be inferred via the disjunctive syllogism rule. ~q and ~w can be inferred via the conjunction rule. ~w and ~q can be inferred via the conjunction rule. u -> w can be inferred via the biconditional elimination rule. w -> u can be inferred via the biconditional elimination rule. ~u can be inferred via the biconditional elimination rule.