Computing Supported Models via Transformation to Stable Models

TL;DR

This paper introduces a transformation method that enables the computation of supported models within standard ASP frameworks, expanding the reasoning capabilities beyond traditional stable models.

Contribution

It presents the first practical transformation technique and implementation for computing supported models using modern ASP solvers like Clingo.

Findings

Supports applications in verification, diagnosis, and planning.

Empirical evaluation shows practical utility and efficiency.

Provides a publicly available tool compatible with standard ASP syntax.

Abstract

Answer Set Programming (ASP) with stable model semantics has proven highly effective for knowledge representation and reasoning. However, the minimality requirement of stable models can be restrictive for applications requiring exploration of non-minimal but logically consistent solution spaces. Supported models, introduced by Apt, Blair, and Walker in 1988, relax this minimality constraint while maintaining a support condition ensuring every true atom is justified by some rule. Despite their theoretical significance, supported models lack practical computational tools integrated with modern ASP solvers. We present a novel transformation-based method enabling computation of supported models using standard ASP infrastructure. Our approach transforms any ground logic program into an equivalent program whose stable models correspond exactly to the supported models of the original program. We implement this transformation for Clingo, providing the first practical tool for computing supported models with state-of-the-art ASP solvers. We demonstrate applications in software verification, medical diagnosis, and planning where supported models enable valuable exploratory reasoning capabilities beyond those provided by stable models. We also provide an empirical evaluation to justify the practical utility of our approach compared to established methods. Our implementation is publicly available and compatible with standard ASP syntax.