13. The method of claim 12 , further comprising: determining one or more tokens from one or more documents, each token comprising a token alphanumerical string that comprises one or more words and appears at least once in the documents; and determining a token order among the tokens.
13. The method of claim 12 , further comprising: determining one or more tokens from one or more documents, each token comprising a token alphanumerical string that comprises one or more words and appears at least once in the documents; and determining a token order among the tokens. 17. The method of claim 13 , wherein generating the target vector representing the target comprises: communicating the target as a query to a search engine; accessing one or more original search results returned by the search engine in response to the query; and calculating a value for each of the tokens based at least in part on a first number of appearances of the token in the documents and a second number of appearances of the token in the original search results, wherein the target vector comprises the values calculated for the tokens ordered according to the token order.