The "Body-Plus" instances are effectively solved by body-based and hybrid lookahead, but not by literal-based lookahead. Due to rule , either or must be contained in any answer set. Considering the additional program rules, body-based and hybrid lookahead detect that is underivable and that rule , where is the instance number, must be used for deriving . That is, body-based and hybrid lookahead infer . In contrast, literal-based lookahead is unable to detect that alternative rules for and are unapplicable and that the body of must be true. Note that the instances are designed to mislead smodels' lookahead-based heuristics.