- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Thu, 21 Mar 2002 15:15:26 -0500
- To: www-webont-wg@w3.org
Here is my initial decision tree document. Note that it doesn't really have a decision tree in it. I decided to format the document slightly differently. I am looking for comments on additions to this document. In particular, I would like more examples of inferences, queries, and syntax possibilities. peter Approaches to OWL Options for OWL, as I see it Syntax 1. RDF triples, XML dialect, other 2. Can definitional information show up not at top level, e.g., john's children are transitive properties? Expressive Power 3. RDFS Frames Simple defined classes (e.g., OWL-lite?) Powerful DL (e.g., current OWL) Model Theory 4. Completely RDF compatible, i.e., interpretations are RDF interpretations with extra conditions Mostly RDF compatible, e.g., compatible for individuals Not necessarily RDF compatible 5. Can classes or restrictions be inferred, e.g., if John is a Student and an Employee does he belong to the intersection of Student and Employee? Problematic Points in the Option Space The combination of 1. Syntax is RDF triples 3. Expressive Power is powerful DL 4. Model theory is completely RDF compatible 5. Classes / restrictions are inferrable. leads to a semantic paradox. This actually doesn't really depend on the fact that the syntax is RDF triples, but instead on the fact that rdf:type is a property and thus can be used in restrictions and on the fact that loops are possible and thus a form of self-reference is possible. The use of 2. Definitional information can show up not at top level can lead to difficult, and difficult-to-implement inference. Potential Proposals for OWL DAML+OIL http://www.w3.org/TR/daml+oil-reference - syntax is RDF triples - expressive power is powerful DL - model theory is (close to) RDF model plus additional conditions - classes / restrictions are not inferrable D+ : DAML+OIL + theory of classes http://www-db.research.bell-labs.com/user/pfps/webont/dplus.html - definitional information can show up not at top level - expressive power is powerful DL - model theory is RDF model plus additional conditions - classes / restrictions are inferrable Old OWL proposal http://lists.w3.org/Archives/Public/www-webont-wg/2002Jan/att-0061/01-swol.text http://www-db.research.bell-labs.com/user/pfps/webont/swol-rdf.text - syntax is XML - definitional information can show up not at top level - expressive power is powerful DL - model theory is close to RDF model theory - classes / restrictions are inferrable Current OWL proposal http://www.cs.vu.nl/~frankh/spool/OWL-first-proposal/ - syntax is abstract, i.e., other - all definitional information has to be at top level - expressive power is powerful DL - model theory is not the same as RDF model theory - classes / restrictions are inferrable Indicative Inferences, Queries, and Expressiveness Inference 1-intersection/ Premises: John is an instance of Student John is an instance of Employee Conclusion: John is an instance of the intersection of Student and Employee Inference 2-restrictions/ Premises: John is an instance of Student with no children Conclusion: John is an instance of the restriction that requires no children Query 3-subclasses/ Given: John is an instance of Student with child Joe Query: return the subclasses of Student Answer Set 1: Student, { John }, Student and Employee, Student and atleast 79 children, ... Answer Set 2: Student Inference 4-trivial/ Given: John is an instance of Student Conclusion: John is not an instance of Student Syntax 5-embedded def/ To be said: all John's children are instances of TransitiveProperty, John has a child that is either Joe or Jim Meaning: Either Joe or Jim is a transitive property SYSTEMS DAML+OIL D+ Old OWL Current OWL 1-intersection no YES YES YES 2-restriction no YES YES YES 3-subclasses 2 1 1 invalid query 4-trivial no YES no no 5-embedded def not possible ? possible not possible
Received on Thursday, 21 March 2002 15:15:39 UTC