4. The method as in claim 1 wherein extracting the first group of words from the phrase includes: parsing the phrase into individual words, and selecting, as the first group of words, less than all of the individual words parsed from the phrase.
5. The method as in claim 4 wherein selecting less that all of the individual words includes: identifying, as the first group of words, a predefined number of uncommon words from the individual words parsed from the phrase.