搜索引擎的问世，解决了信息的定位问题，但是第一代搜索引擎例如AltaVista提供的是全文索引，排名只依据查询向量与文档向量的余弦相似度。
But the first generation of search engines , such as AltaVista , provide full text index . Its ranking strategy is based on the cosine similarity between a query vector and a document vector .
第一代搜索引擎