3. The method of claim 1 , wherein determining, using a document-to-query-to-document model, that the first resource is relevant to a first suggested query different from the initial search query comprises: obtaining a first plurality of previously submitted search queries, each of the first plurality of previously submitted search queries being associated with the first resource identified by the first search result; and selecting a first query from the first plurality of previously submitted search queries as the first suggested query, the first query having at least one term that does not occur in the initial search query.
3. The method of claim 1 , wherein determining, using a document-to-query-to-document model, that the first resource is relevant to a first suggested query different from the initial search query comprises: obtaining a first plurality of previously submitted search queries, each of the first plurality of previously submitted search queries being associated with the first resource identified by the first search result; and selecting a first query from the first plurality of previously submitted search queries as the first suggested query, the first query having at least one term that does not occur in the initial search query. 5. The method of claim 3 , wherein selecting a first query from the first plurality of previously submitted search queries as the first suggested query comprises: determining a respective measure of diversity for each of the first plurality of previously submitted search queries, the respective measure of diversity being based on resources associated with each of the first plurality of previously submitted search queries and resources identified by the plurality of search results responsive to the initial search query; and selecting a first query having a measure of diversity that satisfies a threshold.