题目内容
During crawling, a crawler cannot get to know the complete set of Web pages, therefore it cannot design a good selection policy either.
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Focused crawler or topical crawler is such a crawler to download pages similar to each other.
The anchor text of a link is an instruction to it.
Web Search Engines can analyze anchor text from hyperlinks on Web pages.
If the visited pages are similar to the driving query, the crawler will copy them.
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