51. The computer program product of claim 50 , wherein selecting the candidate query comprises: selecting a query that is prior to the revised query in the query sequence; determining a quality score for the selected query; determining a navigation score for the selected query; and determining the selected query is a candidate query if the quality score of the selected query is less than the quality score threshold and the navigation score of the selected query is less than the navigation score threshold.
50. The computer program product of claim 24 , wherein the candidate query is further selected in response to determining that the quality score for the revised query is greater than the quality score threshold and that the navigation score for the revised query is greater than the navigation score threshold.