> You may find this paper interesting: > > http://www.ai.univ-paris8.fr/~cazenave/APS.ps > > During a dinner at 99'Ing cup in London, we had a discussion > about that, I remember people believing that the number of > liberties is a good indicator of the 'capturability' of a string. > I did not think so, but could not find good arguments. > Here they are. Any comments welcome. Thanks! Don