15 Feb
1997
15 Feb
'97
5:51 p.m.
The following (and the references in it) may be useful: Volger, H., The semantics of disjunctive deductive databases, LNCS 440, 409-421 Spinger, Berlin 1990. Volger, H., Initial and quasi-initial models of theories, Fund.Inform. 18(1993) 339-362. Michel Hebert