民间广为流传的说法是:Google 的创始人佩奇和布林是在1998年的国际互联网大会上听到了李彦宏的演讲,这才受到启发申请了自己的 Page Rank 算法专利。
然而事实上,第七届国际互联网大会是在1998年4月14~18日召开的;而page rank专利则申请于1998年1月——看来佩奇和布林还发明了时间机器呢,就是不知道他们为什么不为时间机器申请个专利。
其实,当时佩奇和布林向李彦宏询问的,是“搜索引擎如何实现商用化”问题——有点社会经验恐怕就会微笑了:这明显是试探潜在竞争对手有没有什么商业计划呢。
李彦宏的专利内容:United States Patent: 5920859
A search engine for retrieving documents pertinent to a query indexes documents in accordance with hyperlinks pointing to those documents. The indexer traverses the hypertext database and finds hypertext information including the address of the document the hyperlinks point to and the anchor text of each hyperlink. The information is stored in an inverted index file, which may also be used to calculate document link vectors for each hyperlink pointing to a particular document. When a query is entered, the search engine finds all document vectors for documents having the query terms in their anchor text. A query vector is also calculated, and the dot product of the query vector and each document link vector is calculated. The dot products relating to a particular document are summed to determine the relevance ranking for each document.
原理简述:根据指向同一篇文档的链接数目为文档排序;然后在搜索时返回排序更靠前的。这很容易理解,就好像学术文档一样,越重要越核心的,被引用次数就越多。
Page Rank 专利内容:United States Patent: 6285999
A method assigns importance ranks to nodes in a linked database, such as any database of documents containing citations, the world wide web or any other hypermedia database. The rank assigned to a document is calculated from the ranks of documents citing it. In addition, the rank of a document is calculated from a constant representing the probability that a browser through the database will randomly jump to the document. The method is particularly useful in enhancing the performance of search engine results for hypermedia databases, such as the world wide web, whose documents have a large variation in quality.
原理简述:先给链接数据库里的链接估算“重要度级别”;然后利用链接本身的重要程度,估计它所指向文章的质量——这也很容易理解,被爱因斯坦引用的文章,肯定比被我引用的可靠的太多。同样的,一个网站越可靠、越严肃,它所链接的文章质量就越高:反过来说也对,你尽管和别人交换链接吧,越和垃圾网站交换链接,你的估值就越低。 |