Towards a programming environment for answer set programming
Enrico Pontelli, Omar Elkhatib · 2007
We present a system (ASP – PROLOG) which provides a tight and well-defined integration of Prolog and Answer Set Programming (ASP). The combined system enhances the expressive power of ASP, allowing us to write programs that reason about dynamic ASP modules and about collections of answer sets. These features are vital in a number of application domains (e.g., planning, scheduling, diagnosis). We describe the design of ASP – PROLOG along with its implementation, realized using CIAO Prolog and Smodels. In addition, we introduce the notion of off-line justification for Answer Set Programming (ASP). Justifications provide a graph-based explanation of the truth value of an atom w.r.t. a given answer set. The notion of justification accounts for the specifics of answer set semantics. The thesis extends also this notion to provide justification of atoms during the computation of an answer set (on-line justification), and presents an integration of on-line justifications within the computation model of S MODELS. Off-line and on-line justifications provide useful tools to enhance understanding of ASP, and they offer a basic data structure to support methodologies and tools for debugging answer set programs. A preliminary implementation has been developed in ASP – PROLOG .