Apart from the limitations on query operators, a query must satisfy an additional condition in order to be used as a live view. Fortunately, this condition is satisfied in most cases, so you should care about it only if your query contains some special expressions, which is relatively rare (except that all classes used in LiveLinq to Objects must satisfy the property notification condition, but that was already mentioned in Using the built-in collection class IndexedCollection<T> (LiveLinq to Objects)|tag=Using_the_built_in_collection_class_IndexedCollectionT_LiveLinq_to_Objects). Unfortunately, this condition is not verified by LiveLinq automatically, so it is your responsibility to make sure it is satisfied. If this condition is not satisfied, your view will not react to changes in its base data. We give two descriptions of this condition: one short, for basic understanding, and another detailed, for advanced usage.