8. The computer-implemented method of claim 7 , wherein measuring similarity between a pair of phrases includes: identifying documents associated with each phrase; determining a number of documents shared by both of the phrases; and computing a ratio between a function of the number of shared documents to a function of a total number of documents associated with both of the phrases.
8. The computer-implemented method of claim 7 , wherein measuring similarity between a pair of phrases includes: identifying documents associated with each phrase; determining a number of documents shared by both of the phrases; and computing a ratio between a function of the number of shared documents to a function of a total number of documents associated with both of the phrases. 9. The computer-implemented method of claim 8 , wherein the documents are identified using uniform resource locators.