After 30 years development , the information query showed to the world as an independent research field and there had been so many fruitful achievement on document content description , index model , matching strategy etc . the appearance of web provided an experiment environment and application context , which people could never imagine before 到80年代,信息检索领域已经在文档内容表示、索引模型、匹配策略等方面取得了丰硕成果。 web的出现为信息查询提供了一个前所未有的试验环境和应用情景,许多web信息检索系统应运而生,例如yahoo