?url_ver=Z39.88-2004&rft_id=10.1007%2F11799573_15&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aulast=Pettorossi&rft.aufirst=Alberto&rft.au=Pettorossi%2C+Alberto&rft.isbn=978-3-540-36635-5&rft.btitle=Logic+Programming&rft.title=Proving+Properties+of+Constraint+Logic+Programs+by+Eliminating+Existential+Variables&rft.date=2006&rft.genre=bookitem