A method and system for use in information retrieval includes, for each of a plurality of terms, selecting a predetermined number of top scoring documents for the term to form a corresponding document set for the term. When a plurality of terms are received, optionally as a query, the system ranks, using an inverse document frequency algorithm, the plurality of terms for importance based on the document sets for the plurality of terms. Then a number of ranked terms are selected based on importance and a union set is formed based on the document sets associated with the selected number of ranked terms.