owl2wsml Translation Notes

This document provides notes on the translation of OWL (RDF/XML) into wsmo by ORDI

ORDI version: 0.21, 26/06/2005

[Properties as Relations]
- problem: OWL does not provide direct equivalents to the WSML attributes. 
Heuristics can be applied to judge that a property can be speculatively judged to be 
an attribute of a class. While this is handy, it couses problems with the semantics
of subProperty.

- resolution: for each OWL property we generate a binary realtion. In case we know its 
domain(s) and/or range(s) the respective list of concepts is placed in its parameter 
definition.

- plan: to find a reasonable strategy for handling subProperty for attributes and
import properties as attributes, when appropriate (e.g. when its domain is defined
as a single class).

- comments: 
--- in case of unknown domain the type of the first argument is owl:Thing
--- in case of unknown range the type of the first argument is owl:Thing if it is a 
owl:ObjectProperty or xsd#string in case of DatatypeProperty
--- for each of the relation features such as 'transitive', 'symettric' etc. \
we associate an axiom 


[Instances without attribute values]
- problem: because of the [Properties as Relaions} issues, the imported instances
do not posses attribute values. 

- resolution: all instance-level statements are translated into
repationInstances of the relation that corresponds to the property.

- plan: to fix it when the the [Properties as Relations] issue get fixed


[Default XML namespace]
- problem: the default XML namespace is not retrieved from the OWL ontology, neither 
can be specified at parse time.

- resolution: we generate a dumy namespace, which have nothing to do with 
the default one from XML

- plan: the idea is to extend wsmo4j Parser interface to allow runtime parameters 
to be passed for each operation.
 

[Cardinality Constraints]
- problem: we don't have an easy way to put cardinality constraints on
relation parameters in WSML

- resolution: for each owl:cardinality(n) we generate two axioms as for
 owl:minCardinality(n) and owl:maxCardinality(n);
 
 
[Min/Max Cardinality] 
- problem: no direct way to constrain this for relation paratemeters

- resolution: 
the translation of owl:maxCardinality(n) looks like:
          ?x memberOf |class| implies 
           exists ?y1,.., ?yn+1( 
            ?x[|prop| hasValue ?y1,..., |prop| hasValue ?yn+1] 
            and (?y1 = ?y2 or ?y1 = ?y3 or ... or ?yn = ?yn+1) 
           ).

the translation of owl:minCardinality(n) looks like:
          ?x memberOf |class| implies 
           exists ?y1,.., ?yn( 
            ?x[|prop| hasValue ?y1,..., |prop| hasValue ?yn] 
            and ?y1 != ?y2 and ?y1 != ?y3 and ... and ?yn-1 != ?yn 
           ).         


[Not Supported OWL class difinitions]
- equivalent 
- union 
- complement
 
 

TRANSLATION HINTS
-----------------


[OWL Restrictions]
For each class that subclasses a Restriction, the respective axiom is generated 
along the set of direct superclasses of the class
 

[hasValue translation]           
the translation of owl:hasValue( |Value| ) looks like:            
          ?x memberOf |class| implies 
           ?x[|prop| hasValue |Value|].


[someValuesFrom translation]           
the translation of owl:someValuesFrom( |class2|, ..., |classN| ) looks like:            
   ?x memberOf |class| implies 
    exists ?y1 (
     ?x[|prop| hasValue ?y1] and (
     ?y1 memberOf |class2| or .. ?y1 memberOf |classN|) ).
 
 
[allValuesFrom translation]           
the translation of owl:allValuesFrom( |class2|, ..., |classN| ) looks like:            
   ?x memberOf |class| implies (
     ?x[|prop| hasValue ?y1] implies (
     ?y1 memberOf |class2| or .. ?y1 memberOf |classN|) ).