The region connection calculus (RCC) is intended to serve for qualitative spatial representation and reasoning. RCC abstractly describes regions (in Euclidean space, or in a topological space) by their possible relations to each other. RCC8 consists of 8 basic relations that are possible between two regions:
From these basic relations, combinations can be built. For example, proper part (PP) is the union of TPP and NTPP.
The composition table of RCC8 are as follows:
The RCC8 calculus is intended for reasoning about spatial configurations. Consider the following example: two houses are connected via a road. Each house is located on an own property. The first house possibly touches the boundary of the property; the second one surely does not. What can we infer about the relation of the second property to the road?
The spatial configuration can be formalized in RCC8 as the following constraint network:
Using the RCC8 composition table and the path-consistency algorithm, we can refine the network in the following way:
That is, the road either overlaps with the second property, or is even (tangential) part of it.
Other versions of the region connection calculus include RCC5 (with only five basic relations - the distinction whether two regions touch each other are ignored) and RCC23 (which allows reasoning about convexity).
RCC8 has been partially implemented in GeoSPARQL as described below: