A Mereological Approach to Representing Spatial Vagueness*

Spatial reasoning is crucial in many AI application domains, such as robotics, qualitative and naive physics, and some types of planning . Qualitative reasoning is often required ; and in many of these cases, uncertainty or imprecision about the spatial extent of particular entities has to be represented and coped with . This paper develops an axiomatisation of a relation of `crisping' (reducing imprecision or vagueness) between pairs of `vague' spatial regions : those with indeterminate boundaries . This axiomatisation is then related to the previously developed 'eggyolk' representation of vagueness, originally designed by (Lehmann and Cohn 1994) for database applications, then applied to expressing spatial vagueness by (Cohn and Gotts 1994) .