US Patent 7725485 Generating query suggestions using contextual information

A search engine receives a query from an end-user. The search engine executes the query on a content database and identifies a set of matching content. The search engine utilizes the matching content to generate a query vector describing the end-user query. The search engine searches a repository of other vectors, called “centroids,” to produce a ranked set of centroids matching the query vector. These centroids are converted into search queries and form a set of candidate queries. The search engine filters the candidate queries to identify ones that are likely to be meaningful to the end-user. The selected candidate queries are returned to the end-user as query suggestions.