ISSUE-157

Last Call Comment: SKOS and OWL 2 analysis

State:
CLOSED
Product:
SKOS
Raised by:
Sean Bechhofer
Opened on:
2008-10-02
Description:
From Peter Patel-Schneider [1]:

I would very much have liked more of SKOS to fit within OWL 2 DL.  I
believe that many of the parts of SKOS that do not fit within OWL 2 DL
are modelling errors.  To show what could be changed I have performed an
analysis (from the reference document, not from the RDF document) of the
bits of SKOS that are not in OWL 1 DL.  For those bits that are not in
OWL 2 DL, I have suggestions on how SKOS could be changed to make it fit
within OWL 2 DL, where I could figure this out.  I believe that having
as much of SKOS in OWL 2 DL would be of benefit to SKOS.  I note that
many of the bits that are not OWL 2 DL are in examples, indicating to me
that they are not so central to SKOS.

Section         Language        What bit / Suggestions to put into OWL 2 DL

skos:Concept    OWL 2 DL        individual/class/property punning (examples)

Concept Schemes OWL 2 DL        individual/ontology "punning" (example)

Lexical Labels  OWL 2 Full      subproperty of rdfs:label
                                  suggestion: don't use rdfs:label

		OWL 2 DL	property disjointness

                not OWL         axiom schema for unique prefLabel
                                  suggestion: include qualified
                                  cardinality restrictions only 
                                  for languages used (defined using
                                  datatype restrictions) 

                OWL 2 DL        individual / class punning (example)

                OWL 2 Full      objects as values of data property (example)
                                  suggestion: don't do this

Notations       extra datatypes	various extra datatypes
                                  suggestion: sort of in OWL 1 DL
 				  already, but unlikely to be supported
                                  by many tools

Documentation   OWL 2 Full      using literal in object property (examples)
                                  suggestion: don't do this

                OWL 2 Full      use of rdf:value (example)
                                  suggestion: don't use rdf:value

                OWL 2 DL        individual/class punning (example)

Semantic Rel's  OWL 2 DL        disjoint properties

Concept Coll'ns OWL 2 Full      ordering with typing
                                  suggestion: see below

Mapping Props   OWL 2 DL        disjoint properties

SKOS X          OWL 2 Full      data property chains
     		      		 suggestion: ??


Here is a way of handling typed ordering that should fit within OWL 2
DL, although I haven't checked all the details.

Declaration( ObjectProperty(skos:firstMember) )
Declaration( ObjectProperty(skos:nextMembers) )
Declaration( ObjectProperty(skos:otherMembers) )
FunctionalProperty(skos:firstMember)
FunctionalProperty(skos:nextMembers)

PropertyDomain( skos:firstMember skos:OrderedCollection )
PropertyRange( skos:firstMember UnionOf(skos:Concept skos:ConceptScheme) ) ??

PropertyDomain( skos:nextMembers skos:OrderedCollection )
PropertyDomain( skos:nextMembers skos:OrderedCollection )
PropertyDomain( skos:otherMembers skos:OrderedCollection )
PropertyDomain( skos:otherMembers skos:OrderedCollection )

SubPropertyOf( skos:nextMembers skos:otherMembers )
SubPropertyOf( PropertyChain(skos:otherMembers skos:nextMembers) skos:otherMembers )

SubPropertyOf( skos:firstMember skos:member )
SubpropertyOf( PropertyChain(skos:otherMembers skos:firstMember) skos:member )

From Peter Patel-Schneider [2]:

The OWL WG notes that some parts of the SKOS specification and some
examples in the reference document do not fit within OWL 2 DL and that
thus may not be fully supported by Semantic Web tools.  The OWL WG
presents the following analysis of the SKOS specification and examples,
to indicate where representation capabilities beyond OWL 1 DL are used.
The OWL WG further notes that in many cases the SKOS specification fits
within OWL 2 DL, but that the examples do not.  The OWL WG suggests
removing those examples that do not fit within OWL 2 DL.

Section         Language        What bit / Suggestions to put into OWL 2 DL

skos:Concept    OWL 2 DL        individual/class/property punning (examples)

Concept Schemes OWL 2 DL        individual/ontology "punning" (example)

Lexical Labels  OWL 2 Full      subproperty of rdfs:label
                                  suggestion: don't use rdfs:label

		OWL 2 DL	property disjointness

                not OWL         axiom schema for unique prefLabel
                                  suggestion: include qualified
                                  cardinality restrictions only 
                                  for languages used (defined using
                                  datatype restrictions) 

                OWL 2 DL        individual / class punning (example)

                OWL 2 Full      objects as values of data property (example)
                                  suggestion: don't do this

Notations       extra datatypes	various extra datatypes
                                  suggestion: sort of in OWL 1 DL
 				  already, but unlikely to be supported
                                  by many tools

Documentation   OWL 2 Full      using literal in object property (examples)
                                  suggestion: don't do this

                OWL 2 Full      use of rdf:value (example)
                                  suggestion: don't use rdf:value

                OWL 2 DL        individual/class punning (example)

Semantic Rel's  OWL 2 DL        disjoint properties

Concept Coll'ns OWL 2 Full      ordering with typing
                                  suggestion: see below

Mapping Props   OWL 2 DL        disjoint properties

SKOS X          OWL 2 Full      data property chains
     		      		 suggestion: ??


Here is a way of handling typed ordering that should fit within OWL 2
DL.

Declaration( ObjectProperty(skos:firstMember) )
Declaration( ObjectProperty(skos:nextMembers) )
Declaration( ObjectProperty(skos:otherMembers) )
FunctionalProperty(skos:firstMember)
FunctionalProperty(skos:nextMembers)

PropertyDomain( skos:firstMember skos:OrderedCollection )
PropertyRange( skos:firstMember UnionOf(skos:Concept skos:ConceptScheme) ) ??

PropertyDomain( skos:nextMembers skos:OrderedCollection )
PropertyDomain( skos:nextMembers skos:OrderedCollection )
PropertyDomain( skos:otherMembers skos:OrderedCollection )
PropertyDomain( skos:otherMembers skos:OrderedCollection )

SubPropertyOf( skos:nextMembers skos:otherMembers )
SubPropertyOf( PropertyChain(skos:otherMembers skos:nextMembers) skos:otherMembers )

SubPropertyOf( skos:firstMember skos:member )
SubpropertyOf( PropertyChain(skos:otherMembers skos:firstMember) skos:member )


[1] http://lists.w3.org/Archives/Public/public-swd-wg/2008Oct/0018.html
[2] http://lists.w3.org/Archives/Public/public-swd-wg/2008Oct/0059.html
Related emails:
  1. ISSUE-157: SKOS and OWL 2 analysis (from dean+cgi@w3.org on 2008-10-02)
  2. Re: personal LC comments on SKOS reference document (from sean.bechhofer@manchester.ac.uk on 2008-10-02)
  3. Re: OWL WG LC comment for SKOS reference document (from sean.bechhofer@manchester.ac.uk on 2008-10-06)
  4. ISSUE-157 draft response (from sean.bechhofer@manchester.ac.uk on 2008-10-06)
  5. Re: ISSUE-157 draft response (from sean.bechhofer@manchester.ac.uk on 2008-10-06)
  6. Status of LC comments (from sean.bechhofer@manchester.ac.uk on 2008-10-06)
  7. Re: ISSUE-157 draft response (from alistair.miles@zoo.ox.ac.uk on 2008-10-07)
  8. Re: ISSUE-155 draft response (from alistair.miles@zoo.ox.ac.uk on 2008-10-07)
  9. [SKOS] Update on Last Call Comments (from alistair.miles@zoo.ox.ac.uk on 2008-12-02)
  10. ISSUE-157 Draft response [was Re: OWL WG LC comment for SKOS reference document] (from schreiber@cs.vu.nl on 2008-12-04)
  11. Re: ISSUE-157 Draft response [was Re: OWL WG LC comment for SKOS reference document] (from alistair.miles@zoo.ox.ac.uk on 2008-12-04)
  12. Re: ISSUE-157 Draft response [was Re: OWL WG LC comment for SKOS reference document] (from aisaac@few.vu.nl on 2008-12-04)
  13. Re: ISSUE-157 Draft response [was Re: OWL WG LC comment for SKOS reference document] (from alistair.miles@zoo.ox.ac.uk on 2008-12-09)
  14. Re: ISSUE-157 Draft response [was Re: OWL WG LC comment for SKOS reference document] (from sean.bechhofer@manchester.ac.uk on 2008-12-09)
  15. meeting record: 2008-12-09 SWD WG Telecon (from swick@w3.org on 2008-12-09)
  16. Re: OWL WG LC comment for SKOS reference document [ISSUE-157] (from sean.bechhofer@manchester.ac.uk on 2008-12-10)
  17. Re: OWL WG LC comment for SKOS reference document [ISSUE-157] (from pfps@research.bell-labs.com on 2008-12-10)
  18. Re: OWL WG LC comment for SKOS reference document [ISSUE-157] (from sean.bechhofer@manchester.ac.uk on 2008-12-11)
  19. Re: OWL WG LC comment for SKOS reference document [ISSUE-157] (from pfps@research.bell-labs.com on 2008-12-11)
  20. Re: OWL WG LC comment for SKOS reference document [ISSUE-157] (from sean.bechhofer@manchester.ac.uk on 2008-12-11)
  21. [ALL] agenda telecon 16 Dec 1600 UTC (from schreiber@cs.vu.nl on 2008-12-15)
  22. [SKOS] SKOS Reference Editors' Draft for Transition to CR (from alistair.miles@zoo.ox.ac.uk on 2008-12-16)
  23. Re: [SKOS] SKOS Reference Editors' Draft for Transition to CR (from sean.bechhofer@manchester.ac.uk on 2008-12-16)
  24. Re: [SKOS] SKOS Reference Editors' Draft for Transition to CR (from alistair.miles@zoo.ox.ac.uk on 2008-12-16)
  25. Re: [SKOS] SKOS Reference Editors' Draft for Transition to CR (from alistair.miles@zoo.ox.ac.uk on 2009-01-29)
  26. [ALL] Agenda - Feb 10 2009 SWD telecon - 1600 UTC (from baker@sub.uni-goettingen.de on 2009-02-09)
  27. Re: Importing SKOS model in ontology editors : problem with OWL full (from alistair.miles@zoo.ox.ac.uk on 2009-04-03)

Related notes:

2008-11-10: ACTION: Accept

2008-12-11: CHANGE-TYPE: Editorial

2008-12-11: RESOLUTION: [[ The OWL WG notes that some parts of the SKOS specification and some examples in the reference document do not fit within OWL 2 DL and that thus may not be fully supported by Semantic Web tools. The OWL WG presents the following analysis of the SKOS specification and examples, to indicate where representation capabilities beyond OWL 1 DL are used. The OWL WG further notes that in many cases the SKOS specification fits within OWL 2 DL, but that the examples do not. The OWL WG suggests removing those examples that do not fit within OWL 2 DL.([from [1]) ]] below you find our responses to the SKOS aspects that are not OWL 2 DL compliant. As a general strategy, we have tried as much as possible to accommodate the alignment with OWL 2 DL. A number of specific points cannot be resolved at this time (see below), so we have decided to POSTPONE this issue. [[ Section: Lexical Labels Language: OWL 2 Full Issue: subproperty of rdfs:label Suggestion: don't use rdfs:label ]] We prefer to keep the subProperty relation; however, we propose to change the type of the lexical label to owl:AnnotationProperty (see resolution of ISSUE 135 [3]). Assuming that OWL 2 DL will support subproperty statements between annotation properties, this change should at least partially solve the issue. [[ Section: Lexical Labels Language: OWL 2 Full Issue: objects as values of data property (example) Suggestion: don't do this ]] We assume you refer to example 17; we propose to remove this example. [[ Section: Documentation Language: OWL 2 Full Issue: using literal in object property (examples) Suggestion: don't do this Section: Documentation Language: OWL 2 Full Issue: use of rdf:value (example) Suggestion: don't use rdf:value ]] As discussed above, the resolution to ISSUE 135 [3] resulted in the SKOS labelling properties being typed as OWL Annotation properties. We propose that the documentation properties be treated similarly. This would then address the issue of the use of a literal with a documentation property. Although this is not then strictly OWL DL compliant, we understand that this will potentially fit with OWL 2 annotations. We propose to remove example 25 (the use of rdf:value). [[ Section: Lexical Labels Language: not OWL Issue: axiom schema for unique prefLabel Suggestion: include qualified cardinality restrictions only for languages used (defined using datatype restrictions) Section: Concept Collections Language: OWL 2 Full Issue: ordering with typing Suggestion: see [1] Section: SKOS XL Language: OWL 2 Full Issue: data property chains Suggestion: ?? ]] We assume these three issues refer to constraints S14 (lexical labels), S35 (ordered collections) and S56, S57 & S58 (SKOS XL). Indeed, these constraints can (currently) not be expressed in OWL. However, these are useful constraints for tool developers and we therefore prefer to keep these in the SKOS Reference.

2009-03-18: COMMENTER-RESPONSE: Accept

2009-03-18: Personal response received from Peter Patel-Schneider.