15. The article of manufacture of claim 10 , wherein selecting the sample utterance-to-text-string mappings from the corpus of utterance-to-text-string mappings based on the compressed word frequencies comprises: determining a first word selection probability for a first word based on a first compressed word frequency of the first word divided by a first word frequency of the first word, wherein the sample utterance-to-text-string mappings include a particular utterance mapped to a particular text string, and wherein the particular text string contains the first word; and selecting the particular utterance based on the first word selection probability.
16. The article of manufacture of claim 15 , wherein selecting the sample utterance-to-text-string mappings from the corpus of utterance-to-text-string mappings based on the compressed word frequencies further comprises: determining a second word selection probability for a second word based on a second compressed word frequency of the second word divided by a second word frequency of the second word, wherein the particular text string also contains the second word; and selecting the particular utterance based on the first word selection probability and second word selection probability.