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Re: ACTION-178: What is ISSUE-116 (Axiomatic Triples for OWL R) about?

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Tue, 12 Aug 2008 10:34:48 -0400
Message-Id: <95FB13AC-D474-459F-9421-6CE11FA10A2E@gmail.com>
Cc: Michael Schneider <schneid@fzi.de>, public-owl-wg Group WG <public-owl-wg@w3.org>, Ivan Herman <ivan@w3.org>, Zhe Wu <alan.wu@oracle.com>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>

Is the assumption that in OWL R/Full that the only way in which one  
determine entailments is to forward chain rules and then look in the  
resultant triples for it?
-Alan

On Aug 12, 2008, at 10:18 AM, Ian Horrocks wrote:

>
> Michael (and Ivan),
>
> I don't have any problem with axiomatic triples in principle.  
> However, while they may be (relatively) harmless in principle, I  
> worry that they could be extremely damaging from an implementation  
> perspective.
>
> Presumably, making axiomatic triples be part of OWL RL (Full) would  
> mean extending the rule set so that it would generate such triples.  
> There could be a very large (perhaps even infinite) number of such  
> triples. This might be a serious burden on implementations and lead  
> to a significant degradation in performance.
>
> I CCed Zhe on this in the hope that we can get a view on this from  
> an OWL R implementer.
>
> ian
>
>
>
>
>
>
> On 11 Aug 2008, at 15:15, Michael Schneider wrote:
>
>> [cc'ing Ivan Hermann as the raiser of ISSUE-116.]
>>
>> Dear WG!
>>
>> At F2F3, ACTION-178 was put on me to explain my understanding of
>>
>>   ISSUE-116: "Should Axiomatic Triples be added to OWL-R Full?"
>>
>> Here is my understanding, after a short explanation what axiomatic  
>> triples are.
>>
>> (A) What are axiomatic triples?
>> -------------------------------
>>
>> These are typical examples of axiomatic triples (taken from RDFS):
>>
>>   (1) rdf:Property rdf:type rdfs:Class
>>   (2) rdf:type rdf:type rdf:Property
>>
>> These axiomatic triples specify the part of the universe to which  
>> certain URIs of the "system vocabulary" belong: 'rdf:Property'  
>> denotes a class, while 'rdf:type' refers to a property.
>>
>> Note that in RDF, there is no real distinction between the  
>> vocabulary specifying the language (such as 'rdf:type'), and the  
>> custom vocabulary used within an ontology. Axiomatic triples  
>> interpret the system vocabulary, by telling what's true for them  
>> independently of the concrete ontology, in which they are used.
>>
>> Axiomatic triples are defined in RDF and RDFS, and also in pD*.  
>> OWL 1 Full also contains lots of axiomatic triples for the OWL  
>> vocabulary, though they are written in a different notation there.
>>
>> (B) Which axiomatic triples do typically exist?
>> -----------------------------------------------
>>
>> Aside of type information (as in the examples (1) and (2)), RDFS  
>> also specifies the domain and range for all properties in the RDFS  
>> vocabulary, e.g.:
>>
>>   (3) rdf:type rdfs:domain rdfs:Resource
>>   (4) rdf:type rdfs:range rdfs:Class
>>
>> (C) What is the scope of the issue?
>> -----------------------------------
>>
>> The main question at F2F3 was whether this issue is also about  
>> *additional* genuine OWL R Full axiomatic triples, or just about  
>> RDFS axiomatic triples. From Ivan's mail it becomes pretty clear  
>> that this issue includes axiomatic triples, which go beyond RDFS  
>> (Ivan confirmed this to me in a private mail). One of his stated  
>> examples is:
>>
>>   "owl:FunctionalProperty,rdfs:subClassOf,rdf:Property"
>>
>> This assertion clearly does *not* exist in RDFS, since  
>> 'owl:FunctionalProperty' doesn't belong to the RDFS vocabulary.  
>> (Whether this example would be a useful axiomatic triple or not  
>> for OWL R Full is not a topic here.)
>>
>> (D) What would be the additional axiomatic triples?
>> ---------------------------------------------------
>>
>> Defining axiomatic triples is in most times a pretty straight  
>> forward task. For all OWL URIs in the OWL R vocabulary the type is  
>> stated (Resource, Class, Property), and for properties also the  
>> range and domain. All axiomatic triples which I have in mind would  
>> follow the examples (1) to (4) above.
>>
>> For example, for 'owl:complementOf', I would propose the axiomatic  
>> triples:
>>
>>     owl:complementOf
>>         rdf:type rdf:Property ;
>>         rdfs:domain rdfs:Class ;
>>         rdfs:range rdfs:Class .
>>
>> Since OWL 2 Full will also have axiomatic triples (the old ones  
>> from OWL 1 Full, and new ones for the new vocabulary), OWL R Full  
>> can simply take what it needs from OWL 2 Full.
>>
>> (E) Could additional axiomatic triples lead to problems?
>> --------------------------------------------------------
>>
>> I suppose that if RDFS axiomatic triples do not already lead to  
>> problems, then additional axiomatic triples for the OWL R  
>> vocabulary will not lead to problems, either.
>>
>> In general, I expect axiomatic triples, as long as they have the  
>> form given in (D), to be semantically harmless (well, mostly  
>> harmless :)).
>>
>>> From a spec'ing effort perspective, adding them is an easy task  
>>> (I am offering to do this, should the WG decide to add them).
>>
>> Regards,
>> Michael
>>
>> --
>> Dipl.-Inform. Michael Schneider
>> FZI Forschungszentrum Informatik Karlsruhe
>> Abtl. Information Process Engineering (IPE)
>> Tel  : +49-721-9654-726
>> Fax  : +49-721-9654-727
>> Email: Michael.Schneider@fzi.de
>> Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555
>>
>> FZI Forschungszentrum Informatik an der Universität Karlsruhe
>> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
>> Tel.: +49-721-9654-0, Fax: +49-721-9654-959
>> Stiftung des bürgerlichen Rechts
>> Az: 14-0563.1 Regierungspräsidium Karlsruhe
>> Vorstand: Rüdiger Dillmann, Michael Flor, Jivka Ovtcharova, Rudi  
>> Studer
>> Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus
>>
>
>
Received on Tuesday, 12 August 2008 14:35:38 GMT

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