VocabGrowth (hereafter VG) selection is modeled after the best methods from previous work , which are based on preferring sentences that contain phrases that occur frequently in unlabeled data and infrequently in the so-far labeled data.
the problem of automatically detecting when to stop AL is a substantial one, discussed at length in the literature (e.g., (Bloodgood and Vijay-Shanker, 2009a;Schohn and Cohn, 2000;Vlachos, 2008)).