Top-Down Query Evaluation for Well-Founded Semantics With Explicit Negation

In this paper we define a sound and complete top--down semantic tree characterization, that includes pruning rules, of the well--founded semantics for programs extended with explicit negation (WFSX), and compare it to other related approaches. It is amenable to a simple implementation (in appendix), and by its nature readily allows pre--processing into Prolog, showing promise as an efficient basis for further development. Because of its properties, which other competing semantics do not fully enjoy, WFSX is a natural candidate to being the semantics of choice for extended logic programs. Namely, it exhibits the structural properties: simplicity, cumulativity, rationality, relevance, partial evaluation, and polynomial complexity for DATALOG. It provides a qualitative representational expressivity that can capture a wide variety of logical reasoning forms, and serve as an instrument for programming them. Since WFSX coincides with the well--founded semantics on normal programs, our method..

Kiel Declarative Programming Days 2013

This report contains the papers presented at the Kiel Declarative Programming Days 2013, held in Kiel (Germany) during September 11-13, 2013. The Kiel Declarative Programming Days 2013 unified the following events: * 20th International Conference on Applications of Declarative Programming and Knowledge Management (INAP 2013) * 22nd International Workshop on Functional and (Constraint) Logic Programming (WFLP 2013) * 27th Workshop on Logic Programming (WLP 2013) All these events are centered around declarative programming, an advanced paradigm for the modeling and solving of complex problems. These specification and implementation methods attracted increasing attention over the last decades, e.g., in the domains of databases and natural language processing, for modeling and processing combinatorial problems, and for high-level programming of complex, in particular, knowledge-based systems