SFB/TR 8: I1-[OntoSpace] OntoSpace Project Report University of Bremen Germany General Ontology Baseline Deliverable D1 I1-[OntoSpace]; Workpackage 1 Scott Farrar and John Bateman December 2005 Version: 2.0 http://www.sfbtr8.uni-bremen.de/I1 e-mail: {farrar,bateman}@uni-bremen.de Roadmap for baseline deliverables D1-D4 The baseline position on ontology, ontology construction, and ontology use adopted in the project I1-[OntoSpace] is set out in a sequence of four deliverables (D1-D4). Each provides an introduction to the respective states of the art and describes the positions within these that I1-[OntoSpace] is adopting for its own work or as proposals for ontology construction within the SFB/TR Ontology Working Group generally. The baseline is made up of the following components: D1 Ontology as such and the principal approaches and methodologies currently available for general ontology construction; D2 The ontologies of space: approaches to representing space that have been taken on ontology and qualitative spatial representation and reasoning; D3 The ontologies motivated by and for language: approaches to representing the kinds of distinctions that treatments of natural language require—particularly but not exclusively those required for spatial language; D4 Inter-Ontology mappings and structuring devices: approaches to constructing on- tologies out of submodules and of relating such submodules in systematic ways. This is the first of these deliverables and introduces the notions of ontology as such. Deliverables D1, D2 and D3 are results of Workpackage 1 as described in the I1-OntoSpace project proposal; D4 is a result of Workpackage 3 and cooperation with project I4-[SPIN]. In general, we will describe deliverables either by the long form ‘I1-[OntoSpace]:D1’ or, when there is no need for disambiguation, the short form ‘D1’. Note: We maintain an extensive and regularly updated webpor- tal for our ontology activities as well as pointers to all kinds of ontologies at the Bremen Ontology Research Group website: http://www.fb10.uni-bremen.de/ontology i Abstract This is a general overview document setting out the basics of ontology design for Project I1-[OntoSpace] and the SFB. First, a discussion of the major design pa- rameters is given in order to familiarize SFB-members with the state of ontological engineering and the issues involved. We then select several key ontologies for dis- cussion along the lines of the parameters introduced. We conclude by setting out our starting assumptions for the ontology designs that will be employed within the project OntoSpace. These assumptions are also proposals for ontology design within the SFB as a whole. Acknowledgements The Cooperative Research Center for Spatial Cognition (Sonderforschungsbereich/Transregio SFB/TR8) of the Universities of Bremen and Freiburg is funded by the Deutsche Forschungs- gemeinschaft (DFG), whose support we gratefully acknowledge. We also acknowledge use- ful comments on earlier drafts especially from Doug Foxvog and also from Thora Tenbrink. Finally, we thank Claudio Masolo and Stefano Borgo for inspiration and advice on all things ontological. ii Contents 1 Introduction: starting points 1 2 Basic Dimensions of Ontology Building 5 2.1 Philosophical approaches . 6 2.2 Meta-level decisions . 7 2.2.1 Subsumption, classes and instances . 8 2.2.2 Set theory and mereology . 9 2.2.3 3D and 4D views of reality . 11 2.2.4 Granularity and Scale . 14 2.3 Representations . 15 2.4 Method . 19 2.5 Computational instantiations of ontologies . 21 3 Sowa’s Ontology 25 3.1 Upper ontology and basics of Sowa’s ontology . 25 3.2 Relations and roles . 27 3.3 Abstractions . 29 3.4 Processes . 29 3.5 Representation . 30 3.6 Summary and discussion of Sowa’s ontology . 30 4 SUMO 31 4.1 SUMO basics and upper ontology . 32 4.2 Mereology in SUMO . 34 4.3 Representation . 35 4.4 Summary and discussion of SUMO . 36 5 Smartkom Ontology 36 5.1 Smartkom upper level . 37 iii 5.2 Smartkom roles . 38 5.3 Smartkom types . 39 5.4 Smartkom relations . 39 5.5 Summary and discussion . 41 6 OpenCyc 41 6.1 OpenCyc basics and upper ontology . 42 6.2 Microtheories . 46 6.3 Mereology in OpenCyc . 48 6.4 Representation . 48 6.5 Summary and discussion of OpenCyc . 50 7 DOLCE 51 7.1 DOLCE basics and upper ontology . 52 7.2 Qualities . 53 7.3 Primitive relations . 55 7.4 Representation . 57 7.5 Summary and discussion of DOLCE . 57 8 BFO 58 8.1 Philosophical underpinnings of BFO . 58 8.2 SNAP . 59 8.3 SPAN . 61 8.4 Trans-ontological relations . 63 8.5 Representation . 63 8.6 Summary and discussion of BFO . 64 9 General Ontology Language: GOL 65 9.1 Basic approach of GOL . 65 9.2 General Formal Ontology: GFO . 66 9.2.1 Categories . 66 iv 9.2.2 Classes . 68 9.2.3 Concrete entities . 68 9.3 GFO relations . 70 9.4 Summary and discussion . 71 10 The D&S extension to DOLCE 71 11 Conclusions and recommendations 75 I Appendix: Parthood basics 87 v List of Figures 1 A basic AI approach: Russell and Norvig’s upper ontology . 7 2 The 4D representation of a car gaining and losing a wheel (West, 2002a) . 12 3 Expressivity hierarchy for ALC classes of description logics . 23 4 Sowa’s upper level ontology lattice . 25 5 Roles in Sowa’s ontology . 27 6 Thematic roles or participants in Sowa’s ontology . 28 7 The process taxonomy in Sowa’s ontology . 29 8 An example conceptual graph . 30 9 The SUMO top-level categories . 31 10 Overall modular organisation of SUMO . 33 11 Various subrelations of ‘part’ in SUMO . 35 12 The upper level ontology used in the Smartkom project . 37 13 The process taxonomy of the Smartkom ontology . 38 14 A portion of the ‘AbstractRepresentationalObject’ taxonomy . 39 15 Smartkom ‘LocationType’ taxonomy . 40 16 Smartkom ‘PhysicalObjectType’ taxonomy . 40 17 OpenCyc’s upper ontology . 43 18 Taxonomy of predicates concerning microtheories . 47 19 Taxonomy of OpenCyc microtheories . 47 20 Parts taxonomy . 49 21 Physical parts taxonomy . 49 22 DOLCE taxonomy: taken from Masolo et al. (2002: 9) . 52 23 Quality and quality spaces (taken from Masolo et al., 2002: 12) . 54 24 DOLCE ontological dependencies (taken from Masolo et al., 2002:22) . 56 25 SNAP top-level categories . 60 26 SPAN top-level categories . 62 27 The top-level categories of the General Formal Ontology . 67 vi 28 The relation taxonomy of General Formal Ontology . 71 29 Description and situation extension to DOLCE (taken from Gangemi and Mika, 2003, figure 1) . 74 30 Hierarchy of mereologies according to strength of commitments; inclusion follows the connecting lines upwards (from Casati and Varzi, 1999, p48) . 89 List of Tables 1 Levels of description suggested by Guarino (1995:632) . 2 2 Some dependences between ontological meta-properties according to the On- toClean methodology . 21 3 Examples of subsumption problems that violate the OntoClean methodology (Guarino and Welty, 2001, Table 3) . 21 4 Axioms of the basic ground mereology . 88 vii I1-[OntoSpace]:D1 1 1 Introduction: starting points This is a general overview document setting out the basics of ontology design that we are proposing for our research projects carried out within the scope of the Collaborative Research Center for Spatial Cognition (SFB/TR8). First, a discussion of the major design parameters is given in order to familiarize SFB-members with the state of ontological engineering and the issues involved. We then select several key ontologies for discussion along the lines of the parameters introduced. Our discussion will mainly focus on current candidates for standardization and re-use within the ontology community, although we focus especially on those that we judge to be of relevance for the SFB. Our particular aim is to set out the starting assumptions for the ontology designs that we will employ within the project OntoSpace; we also consider these as guidelines to be adopted by the Ontology Working Group. The ontologies that we select for review involve ontologies from Artificial Intelligence (e.g., Russell and Norvig, SUMO, Cyc, Smartkom), from philosophy, particularly formal ontology (e.g., Sowa, BFO, GOL), as well as recent drives to combine these with cognitive concerns (e.g., DOLCE). They therefore range from ‘AI-friendly’ efforts such as those of SUMO to the rather more philosophically inclined. We hope that our discussion makes all of them equally accessible, while at the same time bringing out what in particular they can contribute to our own research concerns of developing a broadly based ontological approach to the problems of spatial representation, action and interaction. Our discussion is aimed at readers who wish to gain an overview of what the current ontological options on the market are of what uses those ontologies can be put. For all areas, we give extension references to more detailed sources of information. The first question that we address is a very basic one: why do we want or need an ontology? There has been a steady progression in attempts to understand and model intelligent behavior towards building increasingly explicit and regularized representations of the world in which such behavior is to take place. Early ‘knowledge-intensive’ approaches within AI and cognitive science explored how systems could be constructed to use explicit knowledge representations. Such representations started with more or less ad hoc data structures whose interpretation was often open to question. The classic article of Woods (1975), ‘What’s in a link?’, started a more critical approach to knowledge representation, in which knowledge representations were to be placed on much firmer foundations than hitherto. This was taken further in discussions such as those of Brachman (1977) and Newell (1982).