- From: Michael F Uschold <uschold@gmail.com>
- Date: Mon, 27 Jun 2011 17:37:46 -0700
- To: Markus Krötzsch <markus.kroetzsch@comlab.ox.ac.uk>
- Cc: antoine.zimmermann@insa-lyon.fr, semantic-web@w3.org, voelker@informatik.uni-mannheim.de, "birte.glimm" <birte.glimm@comlab.ox.ac.uk>, sebastian.rudolph@aifb.uni-karlsruhe.de
- Message-ID: <BANLkTi=z8_g-zb2NOtSBeOimc-bq9dRipQ@mail.gmail.com>
On May 23, in a separate
thread<http://permalink.gmane.org/gmane.org.w3c.semantic-web/16554>,
Markus noted:
A more recent, OWL-centric publication on meta-modelling came to my mind
now:
Birte Glimm, Sebastian Rudolph, Johanna Völker:
Integrated Metamodeling and Diagnosis in OWL 2
ISWC 2010, http://www.aifb.kit.edu/web/**Inproceedings3124<http://www.aifb.kit.edu/web/Inproceedings3124>
This is a more comprehensive discussion of the meta-modelling features that
one can practically express in OWL 2, both directly and indirectly.
--
I just read this paper, very interesting. The authors address two
independent shortcomings of OntOWLClean, by Welty.
1. Welty had to keep two separate ontologies, the original one and the meta
one, which had to manually be kept in synch with no semantic connection.
2. reasoning was a real problem, taking too long to get explanations that
can be used to isolate the root cause of OntoDirtiness (i.e OntoClean
constraint viloations)
It is also claimed that these drawbacks "can be overcome now that OWL 2 is
available". In the description of the solution to the first problem, I did
not see any mention of which features of OWL 2 are being used that are
responsible for overcoming the drawbacks, and how the drawback could not be
overcome with OWL 1 Punning is mentioned, and it is certainly very
convenient, but not obviously necessary (to me anyway).
For the second drawback, role chains were used, but the fact that they were
from OWL2 was not highlighted, nor was it argued that it would be impossible
to do that without role chains.
So I'm left without a 'smoking gun' that proves OWL2 metamodelling was the
'culprit' for the additional capabilities. If OWL 2 only allows punning,
then how can any clever approach that works for OWL2 not also work in OWL 1
using different names?
Can anyone spot something that I missed?
NB: These points I mention are not criticisms of the paper because arguments
about the role of OWL 2 is not the point of the paper.
Thanks,
Michael
On Mon, May 23, 2011 at 10:54 PM, Markus Krötzsch <
markus.kroetzsch@comlab.ox.ac.uk> wrote:
> On 19/05/11 20:40, Michael F Uschold wrote:
>
>> I just tried the simple Eagle example in Topbraid Composer. The tool
>> prevents me from entering Eagle both as a class and as an instance of
>> Species, but I can do it manually in a text file, upload it and the
>> SPARQL works as intended.
>>
>> However, is it pure SPARQL, no OWL inferencing. So this happens
>> independently of any OWL 2 DL entailment regime.
>>
>
> Besides David's earlier mail on Composer, I am pretty sure that Protege
> supports punning as well. Current DL reasoners usually have no problem
> handling this feature.
>
>
>
>> I'll have to go poke arodn a bit more to see what if anything the OWL 2
>> DL entailment regime buys me in this context.
>>
>
> A more recent, OWL-centric publication on meta-modelling came to my mind
> now:
>
> Birte Glimm, Sebastian Rudolph, Johanna Völker:
> Integrated Metamodeling and Diagnosis in OWL 2
> ISWC 2010, http://www.aifb.kit.edu/web/**Inproceedings3124<http://www.aifb.kit.edu/web/Inproceedings3124>
>
> This is a more comprehensive discussion of the meta-modelling features that
> one can practically express in OWL 2, both directly and indirectly.
>
> Cheers,
>
> Markus
>
>
> On Thu, May 19, 2011 at 12:25 PM, Michael F Uschold <uschold@gmail.com
>> <mailto:uschold@gmail.com>> wrote:
>>
>> ON the Eagle Example:
>>
>> :Species a owl:Class .
>> :Eagle a :Species, a owl:Class ;
>> rdfs:subClassOf :Animal .
>> :billy a :Eagle .
>>
>> This is valid OWL 2 DL.
>>
>> Then, with a SPARQL 1.1 query with OWL 2 DL entailment regime, I
>> can get
>> the pairs <species,**individualmemberofthespecies>:
>>
>> SELECT ?species, ?member WHERE {
>> ?species a :Species .
>> ?member a ?species .
>> }
>>
>>
>> > Yes, this is allowed.
>>
>> So if this returns ?species as Eagle and ?member as Billy, then
>> SPARQL must not know it is only a pun. It thinks the two are the
>> same. Maybe it is just a syntactic link with little or no semantic
>> import.Intriguing. I'll have to try this out.
>>
>> This is a bit better than I thought. Thanks for the clarification.
>>
>>
>> On Thu, May 19, 2011 at 12:01 PM, Markus Krötzsch
>> <markus.kroetzsch@comlab.ox.**ac.uk <markus.kroetzsch@comlab.ox.ac.uk>
>> <mailto:markus.kroetzsch@**comlab.ox.ac.uk<markus.kroetzsch@comlab.ox.ac.uk>>>
>> wrote:
>>
>> On 19/05/11 18:58, Antoine Zimmermann wrote:
>>
>> First, thanks to you Michael and Markus for your replies.
>>
>> Now, Michael,
>>
>> <snip>
>>
>>
>>
>> Fortunately, OWL 2 now allows a useful form of
>> simple meta-modelling
>> now,
>> so that you can indeed have meta classes and use
>> classes as subjects and
>> objects of properties.
>>
>>
>> The logical inferences that OWL 2 DL tools draw from
>> this are limited,
>> but
>>
>> may still be more than what any particular OWL 2
>> Full reasoner would
>> give
>> you (depends on the OWL 2 Full reasoner you have --
>> I am not aware of
>> much
>> implementation work there beyond OWL 2 RL).
>>
>>
>> Hmm, I know there is some limited punning, but these are
>> two different
>> things, not one thing appearing in two different places.
>> The inference is
>> very limited.
>>
>>
>> What Markus says here I guess is that, in spite of the
>> limitations of
>> the punning mechanism, a full-fledged OWL 2 DL reasoners
>> will likely
>> infer more things than *currently existing* incomplete OWL
>> Full reasoners.
>>
>>
>> Right. We know that there cannot be a tool that computes all
>> consequences of OWL with "proper" meta modelling, and we also
>> know that some forms of meta modelling can even lead to
>> intricate inconsistencies that make the whole ontology language
>> paradoxical (PF Patel-Schneider's paper "Building the Semantic
>> Web Tower from RDF Straw" alludes to this issue). So it seems
>> that a tool that obtains all consequences of plain OWL
>> constructs, and that can still handle some meta modelling is not
>> such a bad choice, even if it is called "OWL DL reasoner" ;-)
>>
>>
>>
>>
>> I don't think there is a way to nicely handle the
>> species example where
>> Species is a class with instance Eagle with instances
>> being individual
>> eagles.
>>
>>
>> No problem:
>>
>> :Species a owl:Class .
>> :Eagle a :Species, a owl:Class ;
>> rdfs:subClassOf :Animal .
>> :billy a :Eagle .
>>
>> This is valid OWL 2 DL.
>>
>> Then, with a SPARQL 1.1 query with OWL 2 DL entailment
>> regime, I can get
>> the pairs <species,**individualmemberofthespecies>:
>>
>> SELECT ?species, ?member WHERE {
>> ?species a :Species .
>> ?member a ?species .
>> }
>>
>>
>> Yes, this is allowed.
>>
>>
>>
>>
>> I also do not think there is a robust solution to the
>> classes as values
>> problem.
>>
>>
>> What do you mean by "classes as values problem"?
>>
>>
>> An insightful discussion of meta modelling semantics
>> -- the one of
>> OWL 2 DL
>> (punning) and a stronger one -- is found in the paper:
>>
>> Boris Motik. On the Properties of Metamodeling in
>> OWL. Journal of
>> Logic and
>> Computation, 17(4):617–637, 2007.
>>
>>
>> Thanks, I just had a look. It is intersting, and geared
>> more for the
>> theorist than the practitioner. Do you know of a more
>> practice-focused
>> paper that gives examples of what you can and cannot do
>> with OWL2
>> metamodelling, compared to OWL-Full?
>>
>>
>> Indeed, this paper is more on the logical side of the
>> discussion, though I still found it quite accessible.
>> Especially, it has some examples of consequences that one looses
>> under the weak meta modelling of OWL 2.
>>
>> I am not aware of a treatment of this issue that is using OWL or
>> RDF terminology. This may not make it easier to understand,
>> since the issues of metamodelling are often complicated by
>> nature -- the straw tower paper mentioned above uses the RDF
>> data model but still requires some thought to understand the key
>> issues raised there.
>>
>>
>>
>>
>> A big advantage of OWL 2 DL in this respect is that
>> it makes it legal to
>> state such meta-knowledge without violating any
>> constraints of the
>> language.
>> The OWL Full semantics may still formally lead to
>> more consequences,
>> but in
>> practice what matters is how many of the total
>> consequence any tool will
>> actually give. So the DL approach could be a good
>> compromise
>> (especially to
>> "make meaning clear" beyond purely logical/formal
>> aspects).
>>
>>
>> I'm not sure what you mean by "make meaning clear" as a
>> good DL
>> compromise.
>> The example from that paper is the need to represent
>> Eagle as an instance
>> of Species so you can e.g. say it is on the engangered
>> list. DL forces
>> you
>> to represent Eagle as an as an individual that can not
>> ever have any
>> instances. But this is patently untrue -- to that
>> extent, it obfusticates
>> meaning. If OWL2 metamodellign lets me do this, I'll be
>> surprised and
>> delighted.
>>
>>
>> Punning means that you can use the URI of an individual in
>> place of the
>> URI of a class. Therefore, :Eagle, as a class, can have
>> instances (like
>> :billy above) and as an individual it can belong to a class
>> (like
>> :Species). However, :Eagle-the-individual is different from
>> :Eagle-the-class, although they share the same identifier.
>>
>>
>> Exactly. This is of course a cheap form of meta modelling, but
>> it seems that it goes a surprisingly long way in practice. Many
>> use cases are really about modelling several "layers" of the
>> domain of interest, but have only little interaction between
>> these layers. Here is an example where one would see the
>> limitation:
>>
>> Assume you have Eagle and Hawk as classes, and you have an
>> individual Tweety who is said to have the species Eagle, and to
>> have the species Hawk (as individuals). Assume further that
>> there is a cardinality restriction that requires "has species"
>> to be functional. Then implicitly we derive that Eagle and Hawk
>> are the same individuals. With punning, nothing else happens.
>> With "true" meta modelling, the classes Eagle and Hawk would
>> also be inferred to be the same, with all the consequences that
>> this could have.
>>
>> I am not sure if this is a practically relevant limitation.
>>
>> Cheers,
>>
>> Markus
>>
>>
>>
>>
>> I think the more important case where ontologies go
>> beyond OWL DL is
>> due to
>> the structural constraints related to transitivity
>> and property
>> chains (e.g.
>> it is easy to get forbidden cycles in property chain
>> dependencies).
>> But the
>> interesting difference to the earlier meta-modelling
>> limitations of
>> OWL 1 DL
>> is that in these cases, the semantics of OWL DL is
>> in principle still
>> meaningful and well-defined in its common
>> first-order logic
>> framework. It is
>> simply known that computing consequences of this
>> semantics becomes
>> undecidable, and thus the decidability-loving DL
>> tools reject the inputs
>> right away.
>>
>> But again anybody who would venture to implement OWL
>> Full reasoning
>> could
>> also look into "OWL DL reasoning for ontologies
>> violating the structural
>> restrictions." This task might be easier to solve in
>> practice since one
>> could probably reuse existing algorithms and tools
>> to solve part of the
>> problem. It is also part of ongoing research to
>> weaken the structural
>> restrictions further, so one already knows of
>> complete algorithms
>> that could
>> achieve this in some cases that OWL DL excludes.
>>
>> Also note that "FULL" and "DL" now refer to
>> syntactic languages only.
>> The
>> semantic distinction is now made between "direct
>> semantics" and
>> "RDF-based
>> semantics". This helps a bit to avoid confusion
>> between syntax and
>> semantics. So my last remark was about finding ways
>> to evaluate (more
>> of)
>> OWL 2 FULL under direct semantics.
>>
>> Cheers,
>>
>> Markus
>>
>>
>> I have no hard evidence, but I feel certain that
>> there are plenty of
>> cases when the penalties of OWL Full are on
>> balance small enough
>> compared to the gains of expressive convenience
>> and clarity of OWL
>> Full.
>>
>> I would love to see someone look into this. I
>> would love it if someone
>> tried to create a reasoner that handled OWL Full
>> as efficiently as
>> possible.
>>
>> Notice how many responses you got to this
>> message in the past few
>> weeks?
>> That may reflect how much people in the
>> community care about OWL Full!
>>
>> Michael
>>
>> Michael
>>
>> On Sat, Apr 23, 2011 at 1:05 AM, Antoine Zimmermann
>> <antoine.zimmermann@insa-lyon.**fr<antoine.zimmermann@insa-lyon.fr>
>> <mailto:antoine.zimmermann@**insa-lyon.fr<antoine.zimmermann@insa-lyon.fr>
>> >
>> <mailto:antoine.zimmermann@**insa-lyon.fr<antoine.zimmermann@insa-lyon.fr>
>> <mailto:antoine.zimmermann@**insa-lyon.fr<antoine.zimmermann@insa-lyon.fr>>>>
>> wrote:
>>
>> Dear all,
>>
>>
>> I'm looking for scientific publications related
>> to OWL Full. I'm
>> interested in the following kind of work:
>> - reasoning with OWL Full;
>> - modelling ontologies in OWL Full;
>> - properties of OWL Full, or relationships
>> between OWL Full and
>> other formalisms.
>>
>> I've found some papers about modelling existing
>> ontologies in OWL
>> (for instance, modelling a UML spec or a
>> frame-based ontology in
>> OWL) which happen to fall into OWL Full, but
>> nothing about modelling
>> OWL Full ontologies by design. I found very
>> little about reasoning
>> in OWL Full (with the notable exception of [1],
>> which also relates
>> OWL reasoning to OOP).
>> But the vast majority of papers mentioning OWL
>> Full present it as
>> the language that must be avoided at all cost
>> (usually saying "if we
>> do that, we are in OWL Full" implying "if we do
>> that, we're screwed!").
>>
>> Thanks in advance for your pointers.
>>
>>
>> [1] Seiji Koide and Hideaki Takeda. OWL-Full
>> Reasoning from an
>> Object Oriented Perspective. In R. Mizoguchi, Z.
>> Shi, and F.
>> Giunchiglia (Eds.): ASWC 2006, LNCS 4185, pp.
>> 263–277, 2006.
>> Springer-Verlag Berlin Heidelberg 2006.
>>
>>
>> Regards,
>> --
>> Antoine Zimmermann
>> Researcher at:
>> Laboratoire d'InfoRmatique en Image et Systèmes
>> d'information
>> Database Group
>> 7 Avenue Jean Capelle
>> 69621 Villeurbanne Cedex
>> France
>> Tel: +33(0)4 72 43 61 74
>> <tel:%2B33%280%294%2072%2043%**
>> 2061%2074><tel:%2B33%280%294%**2072%2043%2061%2074>
>>
>> -
>> Fax: +33(0)4 72 43 87 13
>> <tel:%2B33%280%294%2072%2043%**
>> 2087%2013><tel:%2B33%280%294%**2072%2043%2087%2013>
>>
>>
>> Lecturer at:
>> Institut National des Sciences Appliquées de Lyon
>> 20 Avenue Albert Einstein
>> 69621 Villeurbanne Cedex
>> France
>> antoine.zimmermann@insa-lyon.**fr<antoine.zimmermann@insa-lyon.fr>
>> <mailto:antoine.zimmermann@**insa-lyon.fr<antoine.zimmermann@insa-lyon.fr>
>> ><mailto:
>>
>> antoine.zimmermann@insa-lyon.**fr<antoine.zimmermann@insa-lyon.fr>
>> <mailto:antoine.zimmermann@**insa-lyon.fr<antoine.zimmermann@insa-lyon.fr>
>> >>
>>
>> http://zimmer.**aprilfoolsreview.com/<http://zimmer.aprilfoolsreview.com/>
>>
>>
>>
>>
>> --
>> Michael Uschold, PhD
>> Senior Ontology Consultant, Semantic Arts
>> LinkedIn: http://tr.im/limfu
>> Skype, Twitter: UscholdM
>>
>>
>>
>> --
>> Dr. Markus Krötzsch
>> Oxford University Computing Laboratory
>> Room 306, Parks Road, Oxford, OX1 3QD, UK
>> +44 (0)1865 283529
>> <tel:%2B44%20%280%291865%**20283529>
>> http://korrekt.org/
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> --
>> Dr. Markus Krötzsch
>> Oxford University Computing Laboratory
>> Room 306, Parks Road, Oxford, OX1 3QD, UK
>> +44 (0)1865 283529 <tel:%2B44%20%280%291865%**20283529>
>>
>> http://korrekt.org/
>>
>>
>>
>>
>> --
>> Michael Uschold, PhD
>> Senior Ontology Consultant, Semantic Arts
>> LinkedIn: http://tr.im/limfu
>> Skype, Twitter: UscholdM
>>
>>
>>
>>
>> --
>> Michael Uschold, PhD
>> Senior Ontology Consultant, Semantic Arts
>> LinkedIn: http://tr.im/limfu
>> Skype, Twitter: UscholdM
>>
>>
>
> --
> Dr. Markus Krötzsch
> Oxford University Computing Laboratory
> Room 306, Parks Road, Oxford, OX1 3QD, UK
> +44 (0)1865 283529 http://korrekt.org/
>
--
Michael Uschold, PhD
Senior Ontology Consultant, Semantic Arts
LinkedIn: http://tr.im/limfu
Skype, Twitter: UscholdM
Received on Tuesday, 28 June 2011 00:38:17 UTC