Abstract: A facility is described for searching a corpus. The facility receives a query string, and identifies concepts represented in it. The facility accesses an ordered series of query strategy stages, and loops through them beginning with a first stage until a stage is selected. In each iteration of the loop, the facility accesses a set of attributes among the corpus's attributes that is specified by the stage, and performs a pre-search to determine an extent to which concepts among those identified are represented among the values of the attributes of the set. Based on the determined extent, the facility determines whether the query strategy stage is satisfied and, if so, selects it. The facility performs a search to generate a search result identifying items of the corpus having values of at least some of the attributes of the set that each represent at least one of the identified concepts.