51. A system for providing a natural language answer to a natural language question, the system comprising: an interface configured to receive, over a computer network, a query comprising a grammatical question; an interface configured to submit the query to a lookup engine; an interface configured to receive initial search results from the lookup engine, the initial search results comprising a plurality of documents, wherein the initial search results comprise a ranking of the plurality of documents according to relevance; a processor configured to identify, in the plurality of documents, a plurality of candidate sentences; a processor configured to calculate, for each candidate sentence, a measure of commonality between the candidate sentence and the query; a processor configured to assign, to each candidate sentence, a score, wherein the score comprises (1) a rank of the candidate sentence according to the ranking of the plurality of documents, and (2) the measure of commonality between the candidate sentence and the query; a processor configured to sort the candidate sentences according to score, whereby a rating of candidate sentences is produced; and an interface configured to send, over a computer network, a reply to the query, the reply comprising at least a top candidate sentence from the rating of candidate sentences.
51. A system for providing a natural language answer to a natural language question, the system comprising: an interface configured to receive, over a computer network, a query comprising a grammatical question; an interface configured to submit the query to a lookup engine; an interface configured to receive initial search results from the lookup engine, the initial search results comprising a plurality of documents, wherein the initial search results comprise a ranking of the plurality of documents according to relevance; a processor configured to identify, in the plurality of documents, a plurality of candidate sentences; a processor configured to calculate, for each candidate sentence, a measure of commonality between the candidate sentence and the query; a processor configured to assign, to each candidate sentence, a score, wherein the score comprises (1) a rank of the candidate sentence according to the ranking of the plurality of documents, and (2) the measure of commonality between the candidate sentence and the query; a processor configured to sort the candidate sentences according to score, whereby a rating of candidate sentences is produced; and an interface configured to send, over a computer network, a reply to the query, the reply comprising at least a top candidate sentence from the rating of candidate sentences. 54. The system of claim 51 , wherein the measure of commonality comprises a count of common words.