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It's O(1) vs. O(N) |
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:::LSA produces a very serious computation burden on a search engine. Right now, if you type a word at a search engine, it looks the word up in a [[trie]] and finds documents that contain that word in O(1) time (independent of the number of documents in the collection). If you had a search engine that looked up documents in the LSA latent space, it would have to perform high-dimensional nearest neighbor search. LSA is typically used with 100+ dimensions, so none of the [[computational geometry]] speed-ups for nearest neighbor search apply. Therefore, the search would be O(N), where N is the ''number of documents in the collection''. For Google, that would be 8,000,000,000. As you can see, this is disastrous for searching the web. -- [[User:Hike395|hike395]] 06:14, July 22, 2005 (UTC)
:::: Oh ! That's how ! Thank you very much for the explanation. You made my day. [[User:Kh251|KH251]] 09:02, 22 July 2005 (UTC)
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