We generalize a theorem by Francois Fages that describes the relationship between the completion semantics and the answer set semantics for logic programs with negation as failure. The study of this relationship is important in connection with the emergence of answer set programming. Whenever the two semantics are equivalent, answer sets can be computed by a satisfiability solver, and the use of answer set solvers such as smodels and dlv is unnecessary. A logic programming representation of the blocks world due to Ilkka Niemella is discussed as an example.
In Proceedings of International Workshop on Nonmonotonic Reasoning (NMR), pp. 33-35 2000. Springer.

Esra Erdem Ph.D. Alumni esraerdem [at] sabanciuniv edu
Yuliya Lierler Ph.D. Alumni ylierler [at] unomaha edu
Vladimir Lifschitz Faculty vl [at] cs utexas edu