There are some advantages to Boolean retrieval. The results of the model are
very predictable and easy to explain to users. The operands of a Boolean query can
be any document feature, not just words, so it is straightforward to incorporate
metadata such as a document date or document type in the query specification.
From an implementation point of view, Boolean retrieval is usually more efficient
than ranked retrieval because documents can be rapidly eliminated from consideration
in the scoring process.