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It's a small Web

It's a small Web

作者:封梓  时间:2019-03-07 02:19:00  人气:

By Jens Thomas FEWER than 20 clicks of the mouse is all it takes to explore the wild frontiers of the World Wide Web. The Web includes some 800 million documents on computers all over the globe, yet the shortest route between any two Web pages spans no more than 19 hyperlinks, say physicists in Indiana. Albert-László Barabási and his colleagues at the University of Notre Dame created a robot program to discover how documents on the Web are linked to each other. The robot looks at how many outgoing links each document has, and follows them to see where they go. From this information, the researchers created a computer model describing the Web’s connectivity. In this week’s Nature(vol 401, p 131), Barabási and his colleagues report that their robot has found the Web to be a “small-world network”. While each point tends to connect to near neighbours, there are a few connections between distant points (New Scientist, 6 June 1998, p 7). The classic example of a small-world network comes from studies of the links between co-stars in Hollywood movies, as demonstrated by the game that links any film star to the actor Kevin Bacon in less than four moves. And while the Web isn’t quite as tightly connected as Hollywood, Barabási says that in its version of the Kevin Bacon game—navigating between any two randomly chosen documents—you can always reach your target in 19 moves or less. This explains how surfing the Web can sometimes rapidly lead you to what you are looking for. Even if the Web grows tenfold, just 21 hyperlinks will take you to your goal. Automated search engines, which rely on indexing Web pages, and matching a query to words or phrases in their text, are becoming increasingly unreliable as the Web expands (New Scientist, 10 July, p 11). “The problem is the amount of information available if you don’t have the human ability to understand it all,” says Oren Etzioni, chief technology officer at Go2Net in Seattle, a company developing tools to help navigate the Web. What’s really needed is a search engine that can surf the Web in an intelligent way to exploit the links between documents and the small-world effect. That’s probably beyond the scope of current expertise in artificial intelligence, says Etzioni. So his team is working on strategies such as designing adaptive websites which automatically rearrange themselves to make popular documents more accessible,