1. ICS-FORTH March 10, 2001 1 Institute of Computer Science Foundation for Research and Technology - Hellas Ontologies and Thesauri - Tools for Effective Information Access Martin Doerr Workshop of the Human Network for Cultural Informatics Heraklion, Crete

2. ICS-FORTH March 10, 2001 2 Ontologies and Thesauri Problem Statement  Explanation of a term:  What is an ushebti, what a shawabty ?  What did it mean, and when?  What was is made for?  How was it made?  Where was it used ?  Ideas, concepts, rather than words  Multiple aspects of interest !

3. ICS-FORTH March 10, 2001 3 Ontologies and Thesauri Problem Statement  Searching for comparative Studies  How do I spell It? Ushabti, ushabty, ushebti, shawtaby? Will it be written the same everywhere?  Should I call it : “grave goods”(AAT), “burial figurines”,“dolls”, “afterlife helpers”, “personality surrogate”, “burial ritual”?  And what about “xαρώνειο, δανάκη” ?  Should I call it: “toll”, “cheap coin”, “afterlife helper”, “corpse equipment”, “burial gift”, “burial rites” ?  Would be “grave goods” distinctive enough?

4. ICS-FORTH March 10, 2001 4 Ontologies and Thesauri Problem Statement  How to find the characteristic term itself ?  How to discover related literature ?  Relevant abstractions are not standardized  How to make statistics even about the same item?  The same items can be referred in a thousand ways  How to do comparative studies by features ?  Implicit features are not declared, explicit features need systematic documentation

5. ICS-FORTH March 10, 2001 5 Ontologies and Thesauri Problem Statement  Find well defined concepts  uniquely identifiable without dialogue  with wide agreement  for reproducible agreement between classification and retrieval  Co-operative work on shared knowledge bases (Knowledge Organisation Systems, KOS):  knowledge elicitation from experts  many small agreements and data integration  structural evolution  publication - incorporation at user sites

6. ICS-FORTH March 10, 2001 6 Ontologies and Thesauri Usage Environment? User’s Authority Target AuthoritiesCMSCollections old version specialised Distributed Retrieval Local Term Agreed-on Term foreign language

7. ICS-FORTH March 10, 2001 7 Ontologies and Thesauri About Thesauri  Thesauri: find good terms by associations  Peter Mark Roget,1852, “Thesaurus of English Words and Phrases”  Linguistic thesauri  TEI, FDIS ISO12620, MARTIF, VHG  Dictionary editing, term based, presentation oriented  Conceptual thesauri  From library science, subject classification  Ranganathan 1925-1965: priority of concept. Confusion of Idea plane - Verbal plane - Notational plane hinders analysis and problem solution  ISO2788, ISO5964, ISO2709, e.g. AAT

8. ICS-FORTH March 10, 2001 8 Ontologies and Thesauri About Thesauri Intrathesaurus relations (ISO 2788) Hierarchical Relations (from Descriptor, to Descriptor) BT (Broader Term) BTP (Broader Term Partitive) BTG (Broader Term Generic ) = actual BT Associative Relations (from Descriptor, to Descriptor) RT (Related Term) Equivalence Relations (from Descriptor, to Term) ALT (Alternative Term) UF (Used For Term)

9. ICS-FORTH March 10, 2001 9 Ontologies and Thesauri Broader Term Hierarchies

10. ICS-FORTH March 10, 2001 10 Ontologies and Thesauri About Thesauri  Concepts identify sets of real world objects  Concepts are identified by scope notes, literature references, examples, images – NOT by terms!  Terms (noun phrases) are used  by social groups to refer to concepts  Links express opinions and differences  about set relation between concepts, subsumption, disjointness etc.  about term usage

11. ICS-FORTH March 10, 2001 11 Ontologies and Thesauri Example, problems of Monohierarchy

12. ICS-FORTH March 10, 2001 12 Ontologies and Thesauri Concepts are organized in Facets  Fundamental category, major facet, basic facet:  Ranganathan: Personality, Matter, Energy, Space, Time  CIDOC CRM: Period, Physical Entity, Conceptual Object, Actor, Place, Time-Span, Type, Material, Language  AAT: Objects, Agents, Activities, Styles and Periods, Materials, Physical Attributes, Associated Concepts.  Syntactic element of an indexing expression: e.g. subdivision by period, geography, genre (MARC): “history of painting in 19 th century Greece”, or AAT: “fencing + swords”.

13. ICS-FORTH March 10, 2001 13 Ontologies and Thesauri About Minor Facets  “Minor facets” provide explicit context criteria:  E.g. MDA Archeological Thesaurus: armour by construction : scale armour armour by form : cuirass armour by function : parade armour  A striking example for explicit use of aspect: SHIC — Social, Historical and Industrial Classification — a “pure”, homogeneous thesaurus of human activities — used by British museums to classify artifacts !

14. ICS-FORTH March 10, 2001 14 Ontologies and Thesauri Polydeykes  Directorate of Monuments Record and Publications of the Greek Ministry of Culture develops the “Polydeykes”, in collaboration ICS- FORTH:  Basic Facets:  Kosmos, the world as subject  Living Nature, as historical subject  Culture and Civilization  Space  Time  Creations, the man-made world — Immobile objects — mobile objects — conceptual works — Associative concepts: Stylistic, physical and technical characteristics

15. ICS-FORTH March 10, 2001 15 Thesauri in Archeology Polydeykes  Example: Aspects of Immobile Objects:  “Είδος”, the “design models” of the past (form dominated).  “Ενότητα”, units with respect to social or functional role  “Στοιχεία”, constructive and morphological characteristics: — “τμήματα”, segments/ sections — composition: dependent and independent parts — styles — shapes  Pre-combined in the upper abstraction levels to a complete grid for the classification of characteristic terms and for object classification – consistent but heavy.

16. ICS-FORTH March 10, 2001 16 Ontologies and Thesauri Polyhierarchies instead of Minor Facets objects swords sword-like objects foils (swords) weapons sword-like Fighting and hunting cutting and thrusting fencing cutting and thrusting weapons Fencing swords Wooden swords Wooden Term specialization Criteria assignment

17. ICS-FORTH March 10, 2001 17 Ontologies and Thesauri Ontologies  Formal ontologies: mathematical models for thesaurus relationships  Concepts are correlated with sets of objects  BT/NT => IsA/ subsumption  RT => open number of “roles”/properties/attributes (like “produces”, “used by”, “made for”).  Allow for machine-processable definitions: — Fencing sword = sword used for: fencing” — Weapon = object used for: fighting or hunting — Mother = human & female & which has born: human

18. ICS-FORTH March 10, 2001 18 Ontologies and Thesauri Ontologies  Formal Ontologies are the natural extension of thesauri  Allow for dynamic unambiguous concept formation => multiplication of available vocabulary (in contrast to post- coordination like “grinding+factory)  Allow for machine-based inferencing => multiplication of manageable amounts.  Allow for interpretation of data structures (tables, fields, tags, classes, attributes etc.) and terms => help data interoperability

19. ICS-FORTH March 10, 2001 19 Ontologies and Thesauri Conclusions  Thesauri and ontologies for information systems are retrieval tools, not terminology dictionaries (concepts often different from expert terminology).  Thesaurus structure must be functional, polyhierarchical.  Thesaurus concepts are a matter of agreement.  Indexing data records is different from scholarly classification.  Try to correlate different (foreign) thesauri !  Formal ontologies are the next step. Thesaurus editors: preserve as much knowledge as possible!