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(i) <-> r. r <-> s. forall z: ~Q(z).
Q(i) -> r can be inferred via the biconditional elimination rule. r -> s can be inferred via the biconditional elimination rule. r -> Q(i) can be inferred via the biconditional elimination rule. s -> r can be inferred via the biconditional elimination rule.