17. The system of claim 11 , wherein the operations further comprise: computing a score for each candidate entity text string of a plurality of candidate entity text strings for the first document; ranking the candidate entity text strings according to the computed scores; and associating one or more highest-ranked candidate entity text strings as the one or more entity text strings associated with the document.
17. The system of claim 11 , wherein the operations further comprise: computing a score for each candidate entity text string of a plurality of candidate entity text strings for the first document; ranking the candidate entity text strings according to the computed scores; and associating one or more highest-ranked candidate entity text strings as the one or more entity text strings associated with the document. 18. The system of claim 17 , wherein computing the score for each candidate entity text string of the plurality of candidate entity text strings for the document comprises: receiving an initial score for the candidate entity text string; and determining whether the candidate entity text string occurs in a title of the document; and computing the score for the candidate entity text string including increasing the initial score for the candidate entity text string if the candidate entity text string occurs in the title of the document.