  This paper introduces a new annotated corpus based on an existing informal
text corpus: the NUS SMS Corpus (Chen and Kan, 2013). The new corpus includes
76,490 noun phrases from 26,500 SMS messages, annotated by university students.
We then explored several graphical models, including a novel variant of the
semi-Markov conditional random fields (semi-CRF) for the task of noun phrase
chunking. We demonstrated through empirical evaluations on the new dataset that
the new variant yielded similar accuracy but ran in significantly lower running
time compared to the conventional semi-CRF.
