The ‘Egg-Yolk’ Representation of Regions with Indeterminate Boundaries
Anthony G. Cohn, Nicholas Mark Gotts · 2020
This chapter explores how best to deal with vagueness in spatial representation and reasoning, particularly within the framework of ‘RCC theory’, which provides a representation of topological properties and relations in which regions rather than points are taken as primitive. It deals with regions having vague or indeterminate boundaries but with a known location, not with vaguely located entities. Many of the spatial regions considered in everyday contexts do not have precise boundaries: consider urban areas, clouds of gas, galaxies, and habitats of particular plants. RCC theory as originally devised has no means of representing and reasoning about noncrisp regions. Lehmann and Cohn suggest using two (or possibly more) concentric sub-regions, indicating degrees of ‘membership’ in a vague region. The egg-yolk approach is proposed in the context of the problem of integrating heterogeneous databases, where the notions of ‘regions’ and ‘spatial relations’ are used metaphorically to represent sets of domain entities, and relations between these sets.