conf/sigmod/93 Laurent Vieille A Deductive and Object-Oriented Database System: Why and How? 438 1993 SIGMOD Conference db/conf/sigmod/sigmod93.html#Vieille93 http://doi.acm.org/10.1145/170035.170120 db/conf/sigmod/Vieille93.html SIGMOD93/P438.PDF