How Google knows that “mandriva” was formerly called “mandrake”, to be smart enough to highlight “mandrake” on the results as if I had also searched for “mandrake”?

I don’t think they have added this to a “synonyms table” manually. I believe this was somehow detected automatically. My question is: how the Google software could have detected this automatically?

Update (Feb 2nd 2006): I think I’ve found how this was done. I’ve described my theory in the comments.