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RE: dependency analysis of OWL axioms

From: Obrst, Leo J. <lobrst@mitre.org>
Date: Sat, 15 Nov 2014 22:08:29 +0000
To: Pavel Klinov <pavel.klinov@uni-ulm.de>
CC: Leila Bayoudhi <bayoudhileila@yahoo.fr>, "semantic-web@w3.org" <semantic-web@w3.org>
Message-ID: <FDFBC56B2482EE48850DB651ADF7FEB0353422DF@IMCMBX04.MITRE.ORG>
I agree. So Leila, I will stand by my original statements, and sorry we got distracted. Pavel, if you wish, we can take offline.

Thanks,
Leo

>-----Original Message-----
>From: Pavel Klinov [mailto:pavel.klinov@uni-ulm.de]
>Sent: Saturday, November 15, 2014 4:54 PM
>To: Obrst, Leo J.
>Cc: Pavel Klinov; Leila Bayoudhi; semantic-web@w3.org
>Subject: Re: dependency analysis of OWL axioms
>
>On Sat, Nov 15, 2014 at 10:31 PM, Obrst, Leo J. <lobrst@mitre.org> wrote:
>> No, I would not necessarily translate an OWL ontology to an RDF graph for
>these purposes, but to another graph representation, perhaps, for graph
>dependency analysis.
>
>Then why are we talking about the OWL 2 RDF mapping at all? Remember
>that I asked in the very beginning "In what precisely sense can they
>be
>represented as graphs?" to which you replied with "I understand that
>all OWL ontologies can be represented as graphs, by definition into
>RDF graphs". If you have another graph representation in mind, then I
>go back to my point that it's unclear if your representation can
>faithfully represent arbitrarily complex OWL axioms.
>
>>Also, just to be clear, I would say that the so-called "inferred model" of the
>ontology, i.e., materializing from the base model to the model extended with
>explicit >subsumption, equivalence, etc., relations is probably the way to go.
>
>This is may be useful or completely useless depending on what kind of
>dependency we're talking about. The topic starter gave no indication
>whatsoever that she's interested in inferences. I'm at a loss why
>you're now suggesting inferred model.
>
>>
>> I understand that the semantics of the OWL ontology is not preserved by a
>simple rendition into RDF. In OWL 1, we used to talk about "dark triples", i.e.,
>semantically uninterpretable triples.
>
>Without more details to make it precise, this is a wrong understanding.
>
>Please see http://www.w3.org/TR/owl2-rdf-based-semantics/, especially
>Appendix 7.
>
>>
>> What I was trying to understand was why you thought that an OWL ontology
>could not be represented as a graph (not that it had to be represented as an
>RDF graph).
>
>I did not say "cannot". Representation of an OWL ontology as a graph
>is a not a goal but a tool to achieve some goal. And often a wrong
>tool. But unless you specify what graph representation you have in
>mind, we're both wasting our time here.
>
>Cheers,
>Pavel
>
>>
>> Thanks,
>> Leo
>>
>>>-----Original Message-----
>>>From: Pavel Klinov [mailto:pavel.klinov@uni-ulm.de]
>>>Sent: Saturday, November 15, 2014 4:18 PM
>>>To: Obrst, Leo J.
>>>Cc: Pavel Klinov; Leila Bayoudhi; semantic-web@w3.org
>>>Subject: Re: dependency analysis of OWL axioms
>>>
>>>On Sat, Nov 15, 2014 at 9:52 PM, Obrst, Leo J. <lobrst@mitre.org> wrote:
>>>> Sure, but I do think that is generally very useful, even if it is syntactic.
>>>
>>>First, no, it's not just syntactic; there's semantic compatibility
>>>between OWL and RDF, too.
>>>
>>>Second, it's useful but typically for some specific purposes, like
>>>exchanging OWL documents in RDF or storing OWL ontologies in RDF (e.g.
>>>in triple stores).
>>>
>>>However, when it comes to performing some sort of analysis on an OWL
>>>ontology, such as "what depends on the given axiom", then it is
>>>usually wrong to convert the ontology into RDF and analyse the
>>>resulting RDF graph. You lose the structure of the ontology as a
>>>logical theory and end up with a set of triples, from which it's not
>>>even easy to recover original axioms. Even parsing of RDF back into
>>>OWL isn't all that straightforward, let alone more complicate
>>>analyses.
>>>
>>>>
>>>> Or are you meaning that because first-order logic is semi-decidable it is not
>>>useful to represent axioms and theorems as graphs? I.e., ultimately, that a
>>>graph-dependency analysis of an ontology is not useful?
>>>
>>>Hm, I fail to see how the first question is even relevant to the
>>>discussion. Re: the second, I think one should first understand what's
>>>meant by "dependency" and only then suggest methods. And if by
>>>"graph-dependency analysis of an ontology" you mean "convert it to RDF
>>>and analyse", then I do think it is wrong.
>>>
>>>Pavel
>>>
>>>>
>>>> Thanks,
>>>> Leo
>>>>
>>>>>-----Original Message-----
>>>>>From: Pavel Klinov [mailto:pavel.klinov@uni-ulm.de]
>>>>>Sent: Saturday, November 15, 2014 3:17 PM
>>>>>To: Obrst, Leo J.
>>>>>Cc: Pavel Klinov; Leila Bayoudhi; semantic-web@w3.org
>>>>>Subject: Re: dependency analysis of OWL axioms
>>>>>
>>>>>On Sat, Nov 15, 2014 at 9:01 PM, Obrst, Leo J. <lobrst@mitre.org> wrote:
>>>>>> Pavel,
>>>>>>
>>>>>> How is a GCI not representable as a graph? I understand that all OWL
>>>>>ontologies can be represented as graphs, by definition into RDF graphs. Do
>>>you
>>>>>mean something else?
>>>>>
>>>>>In you read my first reply to you carefully, you will see that I did
>>>>>acknowledge it:
>>>>>
>>>>>"Of course, one can invoke the OWL2RDF mapping and take the resulting
>>>>>set of triples as a (kind of) graph, but I doubt it can be generally
>>>>>useful."
>>>>>
>>>>>But what are you going to do with that graph then?
>>>>>
>>>>>Cheers,
>>>>>Pavel
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Leo
>>>>>>
>>>>>>>-----Original Message-----
>>>>>>>From: Pavel Klinov [mailto:pavel.klinov@uni-ulm.de]
>>>>>>>Sent: Saturday, November 15, 2014 5:08 AM
>>>>>>>To: Obrst, Leo J.
>>>>>>>Cc: Pavel Klinov; Leila Bayoudhi; semantic-web@w3.org
>>>>>>>Subject: Re: dependency analysis of OWL axioms
>>>>>>>
>>>>>>>On Fri, Nov 14, 2014 at 10:51 PM, Obrst, Leo J. <lobrst@mitre.org>
>wrote:
>>>>>>>> Thanks, Pavel.
>>>>>>>>
>>>>>>>> My question is about your comment:
>>>>>>>>
>>>>>>>> "OWL is quite a rich language and one can write very complex axioms
>>>>>which
>>>>>>>don't look anything graph-like."
>>>>>>>>
>>>>>>>> I'd like to know your thoughts on this.
>>>>>>>
>>>>>>>For example, in OWL 2 DL one can take all (class) axioms and re-write
>>>>>>>all that into a single long GCI.
>>>>>>>
>>>>>>>Cheers,
>>>>>>>Pavel
>>>>>>>
>>>>>>>>
>>>>>>>> Thanks!
>>>>>>>> Leo
>>>>>>>>
>>>>>>>>>-----Original Message-----
>>>>>>>>>From: Pavel Klinov [mailto:pavel.klinov@uni-ulm.de]
>>>>>>>>>Sent: Friday, November 14, 2014 3:59 PM
>>>>>>>>>To: Obrst, Leo J.
>>>>>>>>>Cc: Leila Bayoudhi; semantic-web@w3.org
>>>>>>>>>Subject: Re: dependency analysis of OWL axioms
>>>>>>>>>
>>>>>>>>>On Fri, Nov 14, 2014 at 5:42 PM, Obrst, Leo J. <lobrst@mitre.org>
>wrote:
>>>>>>>>>> We had proposed this a number of years ago, but never had time to
>>>go
>>>>>>>down
>>>>>>>>>that path. More towards trying to infer "integrity constraints"
>>>dynamically
>>>>>>>(yes,
>>>>>>>>>OWL is Open World; integrity constraints are Closed World). Finding
>the
>>>>>>>ripple
>>>>>>>>>effect of deleting, adding, moving graph nodes that kind of
>corresponds
>>>to
>>>>>>>>>"referential integrity" (i.e., structural) in the database world. Since all
>>>OWL
>>>>>>>>>ontologies (the axioms) can be represented as graphs, it should be
>>>doable.
>>>>>>>How
>>>>>>>>>efficiently, I don't know.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>I'd be very, very cautious with statements like "OWL axioms can be
>>>>>>>>>represented as graphs". In what precisely sense can they be
>>>>>>>>>represented as graphs? OWL is quite a rich language and one can
>write
>>>>>>>>>very complex axioms which don't look anything graph-like. Of course,
>>>>>>>>>one can invoke the OWL2RDF mapping and take the resulting set of
>>>>>>>>>triples as a (kind of) graph, but I doubt it can be generally useful.
>>>>>>>>>
>>>>>>>>>I can imagine that for some very specific tasks, like decomposition
>>>>>>>>>(as in [1]), a graph-based representation of OWL axioms can be
>>>>>>>>>helpful. But such use cases (and the corresponding representations)
>>>>>>>>>tend to be pretty specific rather than generic.
>>>>>>>>>
>>>>>>>>>Cheers,
>>>>>>>>>Pavel
>>>>>>>>>
>>>>>>>>>[1] Francisco Martín-Recuerda, Dirk Walther: Axiom Dependency
>>>>>>>>>Hypergraphs for Fast Atomic Decomposition of Ontologies.
>Description
>>>>>>>>>Logics 2014: 299-310
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Thanks,
>>>>>>>>>> Leo
>>>>>>>>>>
>>>>>>>>>>>-----Original Message-----
>>>>>>>>>>>From: Leila Bayoudhi [mailto:bayoudhileila@yahoo.fr]
>>>>>>>>>>>Sent: Friday, November 14, 2014 6:36 AM
>>>>>>>>>>>To: semantic-web@w3.org
>>>>>>>>>>>Subject: dependency analysis of OWL axioms
>>>>>>>>>>>
>>>>>>>>>>>Hello
>>>>>>>>>>>I want to know if there is a tool or an approach realizing
>dependency
>>>>>>>>>annalysis
>>>>>>>>>>>of OWL 2 axioms.
>>>>>>>>>>>Example:
>>>>>>>>>>>by removing a subClassOf axioms , I want to know affected ones in
>>>the
>>>>>>>>>>>ontology.
>>>>>>>>>>>Or, can I do it manually by recognizing different types of axioms
>and
>>>>>>>>>expecting
>>>>>>>>>>>relations between them.
>>>>>>>>>>>Thank you for answering me.
>>>>>>>>>>>--398296598-735493131-1415964971=3759
>>>>>>>>>>>Content-Type: text/html; charset=f-8
>>>>>>>>>>>Content-Transfer-Encoding: quoted-printable
>>>>>>>>>>>
>>>>>>>>>>><html><body><div style="color:#000; background-color:#fff; font-
>>>>>>>>>>>family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida
>>>Grande,
>>>>>>>sans-
>>>>>>>>>>>serif;font-size:16px"><div>Hello</div><div>I want to know if there
>is
>>>a
>>>>>>>tool
>>>>>>>>>or
>>>>>>>>>>>an approach realizing dependency annalysis of OWL 2
>>>>>>>>>>>axioms.</div><div>Example:&nbsp;</div><div>by removing a
>>>>>subClassOf
>>>>>>>>>>>axioms , I want to know affected ones in the
>ontology.</div><div>Or,
>>>>>can I
>>>>>>>>>do it
>>>>>>>>>>>manually by recognizing different types of axioms and expecting
>>>>>relations
>>>>>>>>>>>between them.</div><div>Thank you for answering
>>>>>>>>>>>me.</div></div></body></html>
>>>>>>>>>>>--398296598-735493131-1415964971=3759--
>>>>>>>>>>>
>>>>>>>>>>
Received on Saturday, 15 November 2014 22:08:57 UTC

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