关键词: 信息提取, 带有节点频度的文档对象模型树, 节点频度, 语义距离

Abstract: A new module named BF-DOM tree is proposed in this paper，which extends the Document Object Module Tree by adding two properties，i.e.，block node frequency and relativity，to some nodes.Using this module combined with semantic distance，this method extracts the primary content accurately from the same source based on three facts：noise nodes always have high node frequency property within a given website；primary content blocks are often made up of few link words and many text words；useful links are contained in a useful content blocks and have a close semantic distance with page titles.Experiment on eight respective websites shows the proposed method can identify the primary content blocks with higher precision and recall rate both above 96% which is better than the entropy based method.The method can reduce the storage requirement for search engines；thus，result in smaller indexes，faster search time，and better user satisfaction.

Key words: information extraction, Block node Frequency-Document Object Module（BF-DOM） tree, node frequency, semantic distance