The paper is a overview of the major qualitative spatial representation and reasoning techniques. We survey the main aspects of the representation of qualitative knowledge including ontological aspects, topology, distance, orientation and shape. We also consider qualitative spatial reasoning including reasoning about spatial change. Finally there is a discussion of theoretical results and a glimpse of future work. The paper is a revised and condensed version of [33, 34].

The purpose of this paper is to explore some semantic problems related to the use of linguistic ontologies in information systems, and to suggest some organizing principles aimed t o solve such problems. The taxonomic structure of current ontologies is unfortunately quite complicated and hard to understand, especially for what concerns the upper levels. I will focus here on the problem of ISA overloading, which I believe is the main responsible of these difficulties. To this purpose, I will carefully analyze the ontological nature of the categories used in current upper-level structures, considering the necessity of splitting them according to more subtle distinctions or the opportunity of excluding them because of their limited organizational role.

The task of information extraction can be seen as a problem of semantic matching between a user-defined template and a piece of information written in natural language. To this purpose, the ontological assumptions of the template need to be suitably specified, and compared with the ontological implications of the text. So-called "ontologies", consisting of theories of various kinds expressing the meaning of shared vocabularies, begin to be used for this task. This paper addresses the theoretical issues related to the design and use of such ontologies for purposes of information retrieval and extraction. After a discussion on the nature of semantic matching within a model-theoretical framework, we introduce the subject of Formal Ontology, showing how the notions of parthood, integrity, identity, and dependence can be of help in understanding, organizing and formalizing fundamental ontological distinctions. We present then some basic principles for ontology design, and we illustrate a preliminary proposal for a top-level ontology develped according to such principles. As a concrete example of ontology-based information retrieval, we finally report an ongoing experience of use of a large linguistic ontology for the retrieval of object-oriented software components.

This paper presents a formal theory for reasoning about motion of spatial entities, in a qualitative framework. Taking over a theory intended for spatial entities, we enrich it to achieve a theory whose intended models are spatio-temporal entities, an idea sometimes proposed by philosophers or AI authors but never fully exploited. We show what kind of properties usually assumed as desirable parts of any space-time theory are recovered from our model, thus giving a sound theoretical basis for a natural, qualitative representation of motion.

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. Keywords: Region-Connection Calculus, Qualitative Spatial Reasoning, Boolean Connection Algebra, Mer...

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Abstract. This paper is concerned with certain ontological issues in the foundations of geographic representation. It sets out what these basic issues are, describes the tools needed to deal with them, and draws some implications for a general theory of spatial representation. Our approach has ramifications in the domains of mereology, topology, and the theory of location, and the question of the interaction of these three domains within a unified spatial representation theory is addressed. In the final part we also consider the idea of nonstandard geographies, which may be associated with geography under a classical conception in the same sense in which non-standard logics are associated with classical logic. 1.

The need for spatial representations and spatial reasoning is ubiquitous in AI – from robot planning and navigation, to interpreting visual inputs, to understanding natural language – in all these cases the need to represent and reason about spatial aspects of the world is of key importance. Related fields of research, such as geographic information science

We discuss an approach to a theory of physical objects and present a logical theory based on a fundamental distinction between objects and their substrates, i.e. chunks of matter and regions of space. The purpose is to establish the basis of a general ontology of space, matter and physical objects for the domain of mechanical artifacts. An extensional mereological framework is assumed for substrates, whereas physical objects are allowed to change their spatial and material substrate while keeping their identity. Besides the parthood relation, simple self-connected region and congruence (or sphere) are adopted as primitives for the description of space. Only threedimensional regions are assumed in the domain. This paper is a revision and slight modification of [Borgo et al. 1996]. 1.

This paper deals with the issue of the representation of space and motion, and argues that motion can be taken as a primitive notion on which a theory of space can be built, in which every object is an occurrent and has temporal parts. There has been a lot of discussion around the continuants/ occurrents opposition; while some authors have advocated the use of occurrents only for theories of parts and the geometry of common-sense, the few detailed or convincing work that has been devoted to solving the inherent problems of such an approach has made it easy for its detractors to claim it is a dead-end street. We present here a theory of spatio-temporal entities and show how this theory can be used to define a theory of motion. Thus we define a notion of continuity that is more appropriate than mathematical continuity for characterizing motion, and argue that we have here a basis for a theory of spatio-temporal objects.