Well, I was looking for some implementation for Locality-Sensitive Hashing, then I landed on metaoptimize.com from Stackoverflow, thereby clicking on 'Hottest' gave me this first link, and I know that HN people love this sort of stuff, in fact while submitting this link I had this intuition that it has already been submitted earlier. As far as the title is concerned it is intact from the source, but if you consider this template : Free textbooks on [choose subject] , then the only thing which matters and can attract people is 'subject'.