However, manually annotated training data mostly come from the news domain, and the performance can drop severely when the test data shift from newswire to blogs, computer forums, and Internet literature (Liu and Zhang, 2012;).Supervised approaches often have a high requirement on the quality and quantity of annotated corpus, which is always not easy to build.
many previous methods utilize the information of free data which contain limited but useful segmentation information over the Internet, including large-scale unlabeled data, domain-specific lexicons and semi-annotated web pages such as Wikipedia.