ASPMT(QS): Non-Monotonic Spatial Reasoning with Answer Set Programming Modulo Theories
This addresses the need for systematic modeling in dynamic spatial systems, such as in commonsense cognitive robotics and computer-aided design, with a novel integration of methods.
The paper tackled the problem of non-monotonic spatial reasoning in dynamic spatial systems by developing ASPMT(QS), a novel approach based on Answer Set Programming Modulo Theories, and showed it is the only existing system capable of reasoning about indirect spatial effects and integrating geometric and qualitative spatial information.
The systematic modelling of \emph{dynamic spatial systems} [9] is a key requirement in a wide range of application areas such as comonsense cognitive robotics, computer-aided architecture design, dynamic geographic information systems. We present ASPMT(QS), a novel approach and fully-implemented prototype for non-monotonic spatial reasoning ---a crucial requirement within dynamic spatial systems-- based on Answer Set Programming Modulo Theories (ASPMT). ASPMT(QS) consists of a (qualitative) spatial representation module (QS) and a method for turning tight ASPMT instances into Sat Modulo Theories (SMT) instances in order to compute stable models by means of SMT solvers. We formalise and implement concepts of default spatial reasoning and spatial frame axioms using choice formulas. Spatial reasoning is performed by encoding spatial relations as systems of polynomial constraints, and solving via SMT with the theory of real nonlinear arithmetic. We empirically evaluate ASPMT(QS) in comparison with other prominent contemporary spatial reasoning systems. Our results show that ASPMT(QS) is the only existing system that is capable of reasoning about indirect spatial effects (i.e. addressing the ramification problem), and integrating geometric and qualitative spatial information within a non-monotonic spatial reasoning context.