I was a bit disappointed that he didn't mention Kohonen's self-organizing maps, another interesting unsupervised method, or independent component analysis, whic

I was a bit disappointed that he didn't mention Kohonen's self-organizing maps, another interesting unsupervised method, or independent component analysis, which was also used successfully for image feature extraction. Som was also used for a similar document mapping task, the demo is online here: http://websom.hut.fi/websom/milliondemo/html/root.html http://websom.hut.fi/websom/milliondemo/html/root.html