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 or ~s. u <-> q.
s -> q can be inferred via the rewriting rule. u -> q can be inferred via the biconditional elimination rule. q -> u can be inferred via the biconditional elimination rule. ~q can be inferred via the biconditional elimination rule.