0 lacking any clear connection: --
1 expressing a choice between two or more things, where only one is possible: --
We point out that we allow for disjunctive clauses to have empty heads (that is, we allow constraint clauses).
A type in disjunctive normal form is compact if it contains no duplicated conjuncts and all of its conjuncts are compact.
In the following theorem, we formalize a characterization of the preferred semantics in terms of positive disjunctive logic programs and stable model semantics.
The proposed operator, applied iteratively, is shown to characterize the perfect model semantics of stratified disjunctive logic programs.
Such semantics is relatively easy to define and the definition also extends to answer sets of disjunctive logic programs.
However, disjunctive stable model semantics has some drawbacks.
Such a specification is another contribution of this paper, namely a specification expressed as a disjunctive logic program with answer set semantics.
We show how to handle stratified negation in views which may be defined by disjunctive rules, and may contain integrity constraints.
