LSI

I got a demo from Leximancer today. I like the idea that it doesn't use a Lexicon. I couldn't, however, get an answer on what algorithms it uses. Does it use LSI? What is LSI?

From Webopedia: Latent semantic indexing it is an algorithm used by search engines to determine what a page is about outside of specifically matching search query text. The LSI algorithm doesn't actually understand the meanings of words on the page but it can spot patterns of related words. LSI will may return relevant results that don't contain the keyword at all, but those pages with related words.

I think Google one day made a change to use this and everybody panicked cause they were basing their relevance on pure keywords.

Does Leximancer do this?