- From: Michael F Uschold <uschold@gmail.com>
- Date: Tue, 21 Jun 2011 22:27:23 -0700
- To: Markus Krötzsch <markus.kroetzsch@comlab.ox.ac.uk>
- Cc: antoine.zimmermann@insa-lyon.fr, semantic-web@w3.org
- Message-ID: <BANLkTinyp=DrY=Fu1N2UBMikYqWctUAfAA@mail.gmail.com>
Excellent, thanks for the reference to the ISWC paper!
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 Wednesday, 22 June 2011 05:27:52 UTC