随着网络上海量信息的爆炸式增长, 通用搜索引擎面临着索引规模、更新速度和个性化需求等多方面的挑战。面对这些挑战, 适应特定主题和个性化搜索的主题网络爬虫( focusedcrawler or topical crawler) 应运而生。基于主题网络爬虫的搜索引擎( 即第四代搜索引擎) 已经成为当前搜索引擎和Web 信息挖掘中的一个研究热点和难点。(With the explosive growth of network information in Shanghai, general search engines are facing many challenges, such as index scale, speed of update and personalized demand. In the face of these challenges, the focusedcrawler or topical crawler (web crawler) adapted to specific topics and personalized search arises at the historic moment. The search engine based on the subject network crawler (the fourth generation search engine) has become a research hotspot and difficulty in the current search engine and Web information mining.)