Region Connection Calculus Research Articles

A Canonical Model of the Region Connection Calculus

Although the computational properties of the Region Connection Calculus RCC-8 are well studied, reasoning with RCC-8 entails several representational problems. This includes the problem of representing arbitrary spatial regions in a computational framework, leading to the problem of generating a realization of a consistent set of RCC-8 constraints. A further problem is that RCC-8 performs reasoning about topological space, which does not have a particular dimension. Most applications of spatial reasoning, however, deal with two- or three-dimensional space. Therefore, a consistent set of RCC-8 constraints might not be realizable within the desired dimension. In this paper we address these problems and develop a canonical model of RCC-8 which allows a simple representation of regions with respect to a set of RCC-8 constraints, and, further, enables us to generate realizations in any dimension d = 1. For three-and higher-dimensional space this can also be done for internally connected regions.

Spatial relations between indeterminate regions

Systems of relations between regions are an important aspect of formal theories of spatial data. Examples of such relations are part-of, partially overlapping, and disjoint. One particular family of systems is that based on the region-connection calculus (RCC). These systems of relations were originally formulated for ideal regions, not subject to imperfections such as vagueness or indeterminacy. This paper presents two new methods for extending the relations based on the RCC from crisp regions to indeterminate regions. As a formal context for these two methods we develop an algebraic approach to spatial indeterminacy using Łukasiewicz algebras. This algebraic approach provides a generalisation of the “egg-yolk” model of indeterminate regions. The two extension methods which we develop are proved to be equivalent. In particular, it is shown that it is possible to define part-of in terms of connection in the indeterminate case. This generalises a well-known result about crisp RCC regions. Our methods of extension take a relation on crisp regions taking values in the set of two Boolean truth values, and produce a relation on indeterminate regions taking one of three truth values. We discuss how our work might be developed to give more detailed relations taking values in a six-element lattice.

A relation – algebraic approach to the region connection calculus

We explore the relation – algebraic aspects of the region connection calculus (RCC) of Randell et al., Proceedings of the CADE, vol 11, pp. 786–790, Springer, Berlin, 1992a. In particular, we present a refinement of the RCC8 table which shows that the axioms provide for more relations than are listed in the present table. We also show that each RCC model leads to a Boolean algebra. Finally, we prove that a refined version of the RCC5 table has as models all atomless Boolean algebras B with the natural ordering as the “part-of” relation, and that the table is closed under first-order definable relations iff B is homogeneous.

Boolean connection algebras: A new approach to the Region-Connection Calculus

The Region-Connection Calculus (RCC) is a well established formal system for qualitative spatial reasoning. It provides an axiomatization of space which takes regions as primitive, rather than as constructions from sets of points. The paper introduces Boolean connection algebras (BCAs), and proves that these structures are equivalent to models of the RCC axioms. BCAs permit a wealth of results from the theory of lattices and Boolean algebras to be applied to RCC. This is demonstrated by two theorems which provide constructions for BCAs from suitable distributive lattices. It is already well known that regular connected topological spaces yield models of RCC, but the theorems in this paper substantially generalize this result. Additionally, the lattice theoretic techniques used provide the first proof of this result which does not depend on the existence of points in regions.

Approximate qualitative spatial reasoning

Qualitative relations between spatial regions play an importantrole in the representation and manipulation of spatial knowledge.The RCC5 and RCC8 systems of relations,used in the Region-Connection Calculus, are of fundamentalimportance. These two systems deal with ideal regions havingprecisely determined location. However,in many practical examples of spatial reasoning,regions are represented by finite approximations rather than known precisely.Approximations may be given by describing how a regionrelates to cells forming a partition of the space underconsideration. Although the RCC5 and RCC8 systems have beengeneralized to ``egg-yolk'' regions, in order to modelcertain types of vagueness, their extension to regionsapproximated in this way has not been discussed before.This paper presents two methods, the syntactic and the semantic, by which the RCC5 and RCC8 systemsmay be defined for approximate regions. The syntactic uses algebraicoperations on approximate regions which generalize operations on preciseregions. The semantic method makes use of the set of preciseregions which could be the intended interpretation of anapproximate region. Relationships between these two methods arediscussed in detail.alternative to navigation training with a map.

On the complexity of qualitative spatial reasoning: A maximal tractable fragment of the Region Connection Calculus

The computational properties of qualitative spatial reasoning have been investigated to some degree. However, the question of the boundary between polynomial and NP-hard reasoning problems has not been addressed yet. In this paper we explore this boundary in the “Region Connection Calculus” RCC-8. We extend Bennett's encoding of RCC-8 in modal logic. Based on this encoding, we prove that reasoning is NP-complete in general and identify a maximal tractable subset of the relations in RCC-8 that contains all base relations. Further, we show that for this subset path-consistency is sufficient for deciding consistency.

Qualitative Spatial Representation and Reasoning with the Region Connection Calculus

This paper surveys the work of the qualitative spatial reasoning group at the University of Leeds. The group has developed a number of logical calculi for representing and reasoning with qualitativ...