... title, and date. Classified advertise-ments, such as the one in Figure 1(b), also exhibitfield structure, if less rigidly: an ad consists of de-scriptions of attributes of an item or offer, and ... range of linguistic phe-nomena in text, including morphology, parts -of- speech (POS), named entity mentions, and eventopic changes in discourse. An HMM consists of a set of states S, a set of ... procedure willdetect and model at most one of these levels of struc-ture, not necessarily the level desired at the moment.Worse, as experience with part -of- speech and gram-mar learning has shown,...