Polishing Diamonds In Owl2 Ekaw 2008 Acitrezza

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  • A ⊑ psome BA(a)C(x?) A(x?) ∧B(y?) ∧p(x?,y?)
  • Polishing Diamonds In Owl2 Ekaw 2008 Acitrezza

    1. 1. Rinke Hoekstra<br />JoostBreuker<br />University of Amsterdam <br />Polishing Diamonds in OWL 2<br />
    2. 2. Overview<br />Background<br />Ontologies, frameworks and OWL 2<br />Complex concepts<br />Exchange<br />Limitations of OWL 2<br />Design pattern<br />Discussion<br />
    3. 3. Background<br />ESTRELLA Legal Knowledge Interchange Format (LKIF)<br />LKIF Core Ontology<br />http://www.estrellaproject.org/lkif-core<br />Not everything in OWL 2 is an ontology<br />but<br />Not everything that is an ontology fits OWL 2<br />
    4. 4. Not everything in OWL is an ontology<br />Ontology<br />Context independent, intrinsic properties<br />Definitions<br />e.g. basic notions, subsumption hierarchies<br />Framework<br />Context dependent<br />Dependencies, decomposition<br />e.g. part-of hierarchies, scripts, problem solving methods, scenarios, data-structures.<br />
    5. 5. Not everything that is an ontology fits OWL<br />… philosophical perspective<br />e.g. 4D ontologies<br />Complex, structured concepts<br />Artefacts<br />Biological entities (e.g. organs)<br />Exchange <br />Physics: Heat Exchange, Balance/Equilibrium<br />Biology: Metabolism<br />Economy/Law: Transactions, Hohfeldian Squares (rights/duties)<br />
    6. 6. Transaction<br />Characteristics<br />Reciprocity<br />Balance<br />Identity<br />Problem<br />Diamond-shape<br />
    7. 7. OWL 2 DL<br />Description Logics<br />Subset of FOL, model theory<br />Restricted Language<br />Limited Expressiveness<br />Decidability (sound & complete reasoning)<br />Tree-shaped models<br />
    8. 8. A ≡ p2some (B ⊓ p1some D) ⊓ p3some (C ⊓ p4some D) <br />
    9. 9. Why not use rules?<br />Superset<br />SWRL, not decidable<br />Subset<br />OWL 2 RL / DLP / SROIQ Rules, <br />decidable but inexpressive<br />Hybrid<br />DL-Safe rules, decidable but closed world<br />Description Graphs (Motik, 2005)<br />Not standard, no scalable implementation<br />
    10. 10. Polishing Diamonds<br />Polishing Diamonds<br />Fine-tune the set of allowed models<br />Approximate diamond-shaped models<br />Patterns as Templates<br />Emphasise a fixed structure<br />Knowledge Patterns, Content Ontologies Design Patterns<br />Patterns as Recipes<br />Emphasise the design task<br />Steps in ontology design: justification, explanation<br />
    11. 11. Initial Class Definition<br />Transaction ≡ part some Transfer <br />Transfer ≡ actor some Agent ⊓ recipient some Agent <br /> ⊓ object some Object<br />Identify & Enforce<br />Further restriction<br />Only ‘Transfer’ as parts, cardinality restriction on ‘part’?<br />Specific ‘has_transfer’ relation?<br /><ul><li>Qualified Cardinality Restrictions (OWL 2)</li></li></ul><li>Constrain Number of Role Fillers<br />Transaction ≡ part some Transfer ⊓ part min 2 Transfer <br /> ⊑ part exactly 2 Transfer<br />Transfer ≡ actor some Agent ⊓ recipient some Agent <br /> ⊓ object some Object<br /> ⊑ actor exactly 1 Agent ⊓ recipient exactly 1 <br /> Agent ⊓ object exactly 1 Object<br />Identify<br />Equivalence axioms <br />(no universal or max cardinality)<br />Enforce<br />Subclass axioms<br />
    12. 12. Disambiguate Role Fillers<br />Transfer ≡ actor some Agent ⊓ recipient some Agent <br /> ⊓ object some Object<br /> ⊑ actor exactly 1 Agent ⊓ recipient exactly 1 <br /> Agent ⊓ object exactly 1 Object<br />Problem<br />More complex: distinct properties and ranges<br />Actor and recipient may still be the same individual<br />Solution<br />Assert property disjointness<br />
    13. 13. Completion graph<br />
    14. 14. OWL 2 DL Role inclusion axioms<br />Traverse the tree<br />Balance<br />object−o part−o part o object ⊑ value_similar<br />Identity<br />Simulateowl:sameAs<br />actor−o part−o part o recipient ⊑ same_id_as<br />recipient−o part−o part o actor ⊑ same_id_as<br />
    15. 15. Traverse the Tree (1)<br />
    16. 16. Traverse the Tree (2)<br />
    17. 17. Introduce Asymmetry<br />Problem: actor and recipient are inferred to have the same identity<br />Disambiguate branches of tree<br />left_part & right_part<br />Tautological<br />Introduce domain dependence<br />e.g. “Sales Transaction”<br />Domain independent transaction not representable<br />
    18. 18. Sales Transaction<br />Goods_Transfer ⊑ Transfer <br /> ≡ object some Good<br /> ⊑ recipientg some Agent ⊓ <br />actorg some Agent <br />recipientg ⊑ recipient <br />actorg ⊑ actor <br />actor−go part−o part orecipientm ⊑ same_id_as<br />actor−mo part−o part orecipientg ⊑ same_id_as<br />recipient−go part−o part oactorm ⊑ same_id_as<br />recipient−mo part−o part oactorg ⊑ same_id_as<br />
    19. 19.
    20. 20. Discussion<br /><ul><li>Complex concepts</li></ul>Approximate diamond-shaped models<br />Fine-tune the set of valid models<br />Identify individuals in ABox, then <br />Enforce additional restrictions<br />Extensive use of OWL 2 constructs<br />QCR’s, role inclusions<br />Custom identity carrier<br />owl:sameAs(x?,y?) same_id_as(x?,y?) <br />Generalised to<br />Actions, roles, processes<br />

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