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An alternating well-founded semantics for query answering in disjunctive databases.
| Content Provider | CiteSeerX |
|---|---|
| Author | Seipel, Dietmar |
| Abstract | . The well--founded semantics has been introduced for normal databases (i.e. databases that may have default negation in their rule bodies, but do not have disjunctions). In this paper we propose an extension of the well--founded semantics to the disjunctive case. For this purpose we investigate the alternating fixpoint approach of Van Gelder, Ross and Schlipf [16], and develop a suitable generalization to the case of disjunctive rule heads. Given a disjunctive database P, the new alternating well--founded semantics derives a set ADWFSP of partial Herbrand interpretations of P. This set coincides with the set of minimal models if there are no default negations in the database. For general disjunctive databases it is always not empty (if all rule heads are non--empty), i.e. ADWFSP is consistent . The alternating well--founded semantics is very useful for query answering in disjunctive databases. During a fixpoint computation the final set ADWFSP is approximated by a sequence (In)n2I ... |
| File Format | |
| Access Restriction | Open |
| Subject Keyword | Disjunctive Database Query Answering Alternating Well-founded Semantics Default Negation Disjunctive Case Final Set Adwfsp Set Adwfsp Rule Head Fixpoint Approach Fixpoint Computation Partial Herbrand Interpretation Rule Body Normal Database Disjunctive Rule Head Suitable Generalization Van Gelder General Disjunctive Database Minimal Model |
| Content Type | Text |
| Resource Type | Article |
