W3C home > Mailing lists > Public > public-owl-dev@w3.org > April to June 2007

Re: Annotation entailment!

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 29 Jun 2007 10:51:10 -0500
Message-Id: <p06230901c2aad85ad56f@[10.100.0.3]>
To: Denny Vrandecic <dvr@aifb.uni-karlsruhe.de>
Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, OWL list <public-owl-dev@w3.org>

>OK, I checked the specs, and Alan is correct. OK, I can't derive it 
>from the specs (this would require some in-depth reading), but 
>actually there are normative test cases that answer the question 
>pretty clearly (referenced below).
>
>So, owl:sameAs does indeed carry annotation property entailments, i.e.
>
>ex:A rdf:label "Grue".
>ex:A owl:sameAs ex:B.
>--------------------
>ex:B rdf:label "Grue".
>
>*does* hold. Furthermore,
>
>ex:A rdf:label "Grue".
>ex:A owl:equivalentClass ex:B.
>----------------------------
>ex:B rdf:label "Grue".
>
>does *not* hold, but
>
>ex:A rdf:type owl:Class.
>ex:B rdf:type owl:Class.
>ex:A rdf:label "Grue".
>ex:A owl:sameAs ex:B.
>-----------------------
>ex:B rdf:label "Grue".
>
>*does* indeed hold, but only in OWL Full (it's not a valid OWL DL ontology).
>
>I guess
>
>ex:A rdf:label "Grue".
>ex:A owl:equivalentProperty ex:B.
>----------------------------
>ex:B rdf:label "Grue".
>
>does not hold as well.
>
>I find the fact that sameAs and equivalentClass are treated 
>differently with this respect unintuitive, but at least it is well 
>specified :) A well defined spec is the next best thing to an 
>intuitive spec.

Allow me to suggest the appropriate intuition. In RDFS and OWL-Full 
there is a distinction between a class and the (set which is the) 
extension of the class. So two different classes might have the same 
sets of instances and yet still be distinct classes. (This is often 
described by saying that RDFS and OWLFull classes are 'intensional' 
as opposed to 'extensional'. For example, the classes of Human and 
HairlessBiped have the same members, but one might want to 
distinguish them since they have different defining conditions on 
membership. OWL-DL refuses to countenance such a possibility, 
although this may be rectified in OWL 1.1.) Thus there is an 
intuitive distinction in meaning between equivalentClass (having the 
same instances) and sameAs (being exactly the same thing). When, as 
in RDFS and OWL-Full, classes can have properties, one wants to 
preserve this distinction by saying that if A sameAs B then all the 
properties of A are also properties of B (since A and B are the very 
same thing); but this does not follow for A equivalentClass B, since 
A and B might still be distinct even if they do have the same members.

Pat Hayes

>
>Thanks for your help,
>denny
>
>Here are the test cases I derived this from:
><http://www.w3.org/TR/owl-test/byFunction#function-sameAs>
><http://www.w3.org/TR/owl-test/byFunction#function-equivalentClass>
>
>Zitat von Alan Ruttenberg <alanruttenberg@gmail.com>:
>
>>
>>I have recently understood it to be the case that this *is* 
>>entailed.  However, I don't think that it is desirable, and it 
>>seems to be the  case that there is no OWL-DL reasoner that 
>>attempts to be sound and  (otherwise) complete that implements this 
>>behavior, at least that I'm  aware of.
>>
>>What do you think of this behavior? Is it is what you expected or 
>>wanted? If so, I'd be interested hearing about your use case.
>>
>>Until recently it was my (flawed) understanding that statements 
>>involving annotation properties were to be ignored by a reasoner.
>>
>>-Alan
>>
>>
>>On Jun 27, 2007, at 6:06 PM, Denny Vrandecic wrote:
>>
>>>
>>>Does
>>>ex:A rdf:label "Groo".
>>>ex:A owl:sameAs ex:B.
>>>entail
>>>ex:B rdf:label "Groo"?
>>>
>>>i.e. are annotation property instances connected to the URI or the 
>>>underlying individual?

ALL properties in RDF (and all languages encoded in it) are 
properties of the individual denoted by the subject URI, not of the 
URI itself. The only reliable way to refer to a URI is to use an RDF 
literal typed with xsd:anyURI.

Pat

>>>(And respectively for classes and properties)
>>>
>>>Wondering,
>>>denny


-- 
---------------------------------------------------------------------
IHMC		(850)434 8903 or (650)494 3973   home
40 South Alcaniz St.	(850)202 4416   office
Pensacola			(850)202 4440   fax
FL 32502			(850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
Received on Friday, 29 June 2007 15:51:23 GMT

This archive was generated by hypermail 2.3.1 : Wednesday, 27 March 2013 09:32:54 GMT