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: s -> u_1. q_16 or ~u_1. u_1 <-> q_16.
u_1 -> q_16 can be inferred via the rewriting rule. u_1 -> q_16 can be inferred via the biconditional elimination rule. q_16 -> u_1 can be inferred via the biconditional elimination rule.