case Rewrite::MAP_BAG_MAKE: return "MAP_BAG_MAKE";
case Rewrite::MAP_UNION_DISJOINT: return "MAP_UNION_DISJOINT";
case Rewrite::MEMBER: return "MEMBER";
+ case Rewrite::PRODUCT_EMPTY: return "PRODUCT_EMPTY";
case Rewrite::REMOVE_FROM_UNION: return "REMOVE_FROM_UNION";
case Rewrite::REMOVE_MIN: return "REMOVE_MIN";
case Rewrite::REMOVE_RETURN_LEFT: return "REMOVE_RETURN_LEFT";