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_11 -> s. s -> q_11. q_11 <-> s.
q_11 <-> s can be inferred via the biconditional introduction rule. s <-> q_11 can be inferred via the biconditional introduction rule. q_11 -> s can be inferred via the biconditional elimination rule. s -> q_11 can be inferred via the biconditional elimination rule.