John Bateman Till Mossakowski Oliver Kutz Joana Hois

1. BREMEN ONTOLOGY RESEARCH GROUP Ontology Structuring Mechanisms and Ontological Modularityongoing research and targeted applications http://www.sfbtr8.uni-bremen.de http://www.fb10.uni-bremen.de/ontology John Bateman Till Mossakowski Oliver KutzJoana Hois University of Bremen + DKFI, Bremen

2. Overview of our topics today • General orientation and our position on ontologies • The formal framework within which we are working • Examples of ontological modularities and re-use • Conclusions

3. Several Research Areas currently under Investigation • Mobility support • Spatially-embedded tasks • Exploration, Route Planning • Navigation • Interaction with diverse user groups • Disabilities • Age

4. Problem foci • Spatial assistance systems • Route planning and navigation • Real-world environments involving ‘common-sense’ entities • Interfacing with geographic information • Interfacing with language technology • Interfacing with visual presentations (maps) • Interfacing with robotic sensor data • Embodied systems • Human-Robot Interaction

5. Problem • Many different kinds of knowledge are required to get people into the loop in a way that is empowering and enriching rather than restricting

6. Voronoi calculation on a scanned floor plan “where are you?” Voronoi map From SFB/TR8 project: A1-[RoboMap]

7. Sources of relevant knowledge Location-based services Geographic Information Systems Commonsense objects and activities Spatial awareness and understanding Natural language capabilities Robot perception User Knowledge User (dis)abilities

8. Problem restated • Getting these diverse areas of expertise to talk to each other is a serious issue • different communities • different interests • different representations • The kinds of knowledge maintained by such systems are very different

9. Essential idea… • Providing channels to ontologies provides access to detailed contextual ‘world-knowledge’ that does not then have to be worked out again… Ontology Application

10. Many perspectives on ‘reality’: many ontologies space-1 event time space-2 event Ontologically diverse

11. Example of communication problems:When is a road not a road? • Community 1: • transit system designers • roads and highways as connections between destinations (cities, towns, etc.) • Community 2: • environment and wildlife department • species have habitats • habitats have divisions separating them

12. Ontologically mediated inter-operability graph ontology region ontology node node city A species A Hwy 456 city B environment transit system

13. Ontologically mediated inter-operability graph ontology region ontology node node city A species A Hwy 456 city B environment transit system

14. Methodological starting point • There is no sense in which a simple ‘merging’ of the ontologies involved is a sensible strategy to follow

15. Solution we are pursuing • High degree of interoperability between diverse knowledge-rich systems is to be achieved by ontological engineering, taking in: • knowledge of the human world (commonsense) • knowledge of the robot world (programmed, emergent) • geo-knowledge (GML, other standards) • spatial knowledge (spatial calculi) • knowledge of language (linguistics)

16. Ontological diversity inter-ontology mappings landmarks event types time choremes CASL CASL CASL CASL route graphs description CASL

17. Perspectives / Viewsrather than inheritance link in transport network geographical region source of pure water lake recreational area obstacle Alternate theories / ontologies

18. Inter-ontology mappings • ... can only work if there is sufficient content to get hold of! • That is: not a relationship between ‘terms’ but a relationship between ‘theories’. • For this, need deep ontologies, so-called ‘axiomatized ontologies’

19. Choosing between types of ontologies • ‘Light’ ontologies: semantic web? • ‘Heavy’ ontologies: • Rich axiomatization • Formal principles • Well-defined design criteria

20. Our ontological starting point Leo Obrst

21. Theories... • We all have theories... • theories of the world • theories of how buildings are • theories of the best way to get from A to B • theories of how to persuade your boss for a raise • ‘A-ontologies’ set such theories out in an explicit specification.

22. Prerequisites for success • unless you can reason with the axioms: non-starter • unless you can chunk your axioms: non-starter • unless you can parameterize and re-use theories: non-starter • unless you can state relations between the meanings of chunks: non-starter  logic  building theories  structured logic support  inter-theory mappings

23. Essential ingredients we are drawing on in Bremen • Existing ontologies • DOLCE (Masalo/Borgo/Guarino) (for cross-category binding and axiomatization) • BFO (Barry Smith) (for sites, niches and places and for SNAP/SPAN) • GUM (John Bateman) (for linguistic semantics and natural language processing) • State of the art logical tools • CASL + Hets Tool

24. Ontology construction • Axioms are grouped into logically appropriate theories • Theories may be extended via parameterization to achieve semantic re-use • Theories may be created and related by views: theory morphisms Only with this re-use factor can the complexity of distinct axiomatized ontologies really be harnessed and used to scale-up.

25. Approaches to ‘simplifying’ the ontologist’s life... • Making sure that each component of a library of theories only specifies the axioms which are relevant at that point (cf. John Sowa: “That is the whole point of Ockham's razor:  eliminate any axioms that are not absolutely essential to the task at hand.”) • Making sure that unnecessary detail is hidden in ‘upstream’ libraries: CASL • Possibilities for ‘common subsets’: • packages such as our spatial calculi • packages such as DOLCE’s ‘constitution’, ‘participation’, ‘quality spaces’, BFO’s ‘sites’ • language-based generic ontology (GUM)

26. This is essential: because in analysis there are a lot of pieces to put back together!!

27. Combining theories for semantic interpretation driving along the road to Bremen on the right is a church

28. hp o oriented path driving along the roadto Bremen on the right is a church > route graph half-planes physical object occupying a region Combining theories for semantic interpretation

29. OK, go towards the mountains along the main road until you reach a large wooden house. Be careful, the road gets a bit narrow where the old church sticks out. Turn right at the house and, then, at the third intersection, turn right leaving the city limits. Then turn downhill towards the river. At the river, take the ferry over to the café.

30. Theories needed for interpretation OK, go towards the mountainsalong the main road until you reach a large wooden house. Be careful, the road gets a bit narrow where the old church sticks out. Turn rightat the house and, then, at the third intersection, turn rightleaving the city limits. Then turn downhilltowards the river. At the river, take the ferry over to the café. theories of orientation: towards theory of landmarks: mountain theory of structural landmarks / constraints on movement and decisions: (along) the main road theory of destinations: the house theory of shapes of physical objects: narrow road, old church (sticking out) theory of landmarks: the house theories of orientation: right theory of ordered sequences theories of orientation: right theories of regions (administrative): city theory of structural landmarks: intersections theories of orientation: towards theories of topography: slopes theory of landmarks: the river theory of destinations: the café theory of structural landmarks: (over) the river theory of landmarks: river

31. Theories... • Each of these contributions to the meaning of what is being said is considered to draw on a range of more or less related theories of the world… • axiomatised ontologies set such theories out in an explicit specification.

32. IEEE Standard Upper Ontology Working Group John Sowa (email/web discussion)

33. IEEE Standard Upper Ontology Working Group John Sowa (email/web discussion)

34. IEEE Standard Upper Ontology Working Group John Sowa (email/web discussion) • What kinds of ‘modules’ are these? • What is the nature of relationships that can hold between them? • How do these relate to different communities’ theories of the world?

35. A general approach… In the next section of the talk we discuss how we are formalizing these notions of ontological modularity and inter-module relationships. • Formal framework: CASL • Generic framework for describing how ontologies and modules can be related: ‘alignments’ • Some examples

36. CASL - Common Algebraic Specification Language • Standardised first-order specification language; • designed by CoFI “Common Framework Initiative for algebraic specification and development” since 1995 • approved by IFIP WG 1.3 “Foundations of Systems Specifications” (1998), extensive documentation (LNCS 2900, 2960) • various extensions and sublanguages, including higher-order dialects, modal logic, OWL-DL; • supports structured specifications including imports, hiding, renaming, union, extensions, etc.

37. CASL language constructs

38. CASL example: basic • Basic specification of “Services located at rooms”

39. CASL example: structured • Named structured specification of a distance function

40. CASL example: view

41. DOLCE in CASL Lüttich & Mossakowski (FOIS 2004) Primitives GenParthood GenParthood GenMereology

42. DOLCE in CASL Lüttich & Mossakowski (FOIS 2004) Primitives GenParthood spec MEREOLOGY = PRIMITIVES then %%Ad7, Ad8, Ad9 and Ad10 are generated by %% instantiation of GenMereology GENMEREOLOGY [sort T] then GENMEREOLOGY [sort S] then GENMEREOLOGY [sort PD] end GenMereology Mereology

43. The Tool HeTS

44. Varieties of Modules “Parts” of an ontology can be considered a “module” for a variety of reasons: • logically self-sufficient/independent conservativity; • part of a larger “integrated” ontology DDLs, E-connections, etc. • coupling through interface alignments • tradition, convenience, elegance, etc. general structuring techniques Realised through various theory morphisms

45. Shapes of Alignments • we represent various alignments as diagrams of certain “shapes” • connected through “interfaces” • we assume alignment mappings are given • colimits are used for an overall integration • composition of diagrams as composition of alignments • definitional extensions do not add ‘substance’

46. Arrows in Diagrams Structuring mechanism • black: imports; • dashed black:automatically constructed imports • blue: definitional or conservative extensions; Postulating links • dotted red: proof obligations; theorem links; interpretation into theory; • green: = proven “red” obligation;

47. V-alignment through interface • cannot handle subclass alignments

48. W-alignment with bridge ontology • Integration through bridge ontology Person Woman

49. M-alignment: bridges and extensions • Integration through bridge along extensions Woman, Person, Financial_Bank, River_Bank Person, Bank Woman, Bank Person, Bank Person

50. Bibliographical Ontology in DL • logic DL • specBiblio_DL = • Class: Researcher • SubclassOf: name some Thing • ObjectProperty: hasArticle • InverseOf: hasJournal • Class: Article • SubclassOf: author some Thing, • title some Thing, • hasJournal some Journal • Class: Journal • SubclassOf: name some Thing, • hasArticle some Thing, • impactFactor some Thing • end