The document discusses using pattern mining techniques to detect and extract unknown words from Chinese text. It begins with an introduction of the Chinese word segmentation problem and types of unknown words. It then discusses related work on particular and general unknown word extraction methods. The document proposes applying continuity pattern mining to detect unknown words, and using sequential supervised learning and machine learning algorithms to extract unknown words based on natural language and statistical information. Experimental results show the approach achieves better performance than rule-based methods.