Qualitative Reasoning about 2D Cardinal Directions using Answer Set Programming

We introduce a formal framework (called NCDC-ASP) for representing and reasoning about cardinal directions between extended spatial objects on plane, using Answer Set Programming (ASP). NCDC-ASP preserves the meaning of directional relations as in Cardinal Directional Calculus (CDC), provides solutions to all consistency checking problems CDC under various conditions (i.e., complete/incomplete set basic/disjunctive constraints over connected/disconnected objects). In particular, models discretized version problem ASP, finite grid (rather than plane), where we provide new lower bounds size guarantee that it correctly characterizes CDC. addition, has following two novelties important applications. introduces default represent reason background or commonsense knowledge involves qualitative (e.g., "the ice cream truck is by north playground" keyboard normally placed front monitor"). inferred allow inference missing them explanations. illustrate uses usefulness with interesting scenarios from real-world. design develop variety benchmark instances, comprehensively evaluate perspectives computational efficiency.