Recently, the notion of forgetting has drawn considerable attention in the area of Knowledge Representation and Reasoning. The underlying idea is to discard a part of the knowledge base without affecting the derivations on, e.g., atoms that are not to be forgotten. Several recent papers consider forgetting under answer set semantics, but sometimes the well-founded semantics with data complexity...

The well-founded semantics (WFS) for logic programs is one of the few major paradigms for closed-world reasoning. With the advent of the Semantic Web, it is being used as part of rule systems for ontology reasoning, and also investigated as to its usefulness as a semantics for hybrid systems featuring combined openand closed-world reasoning. Even in its most basic form, however, the WFS is unde...

Constructive negation derives constraint answers for non-ground negative literals. Its incorporation into query evaluation under the well-founded semantics introduces two problems. One is the detection of repeated sub-goals and the elimination of redundant answers, which is required in order to guarantee termination. The other is the interaction between constraint answers of non-ground negative...