1. A computer-implemented method for identifying superphrases in a set of candidate phrases with reference to a set of seed phrases, each of the candidate phrases comprising one or more candidate phrase words, and each of the seed phrases comprising one or more seed phrase words, the method comprising: sorting all distinct ones of the seed phrase words in the set of seed phrases; indexing each seed phrase in the set of seed phrases by sorting the corresponding seed phrase words, and indexing the seed phrase with reference to the sorted distinct seed phrase words; and determining whether each candidate phrase is a superphrase of one or more of the seed phrases by sorting only the corresponding candidate phrase words included among the distinct seed phrase words, and determining whether all of the seed phrase words of any of the indexed seed phrases are included among the sorted candidate phrase words.