- From: Markus Krötzsch <markus.kroetzsch@comlab.ox.ac.uk>
- Date: Tue, 24 May 2011 06:54:36 +0100
- To: Michael F Uschold <uschold@gmail.com>
- CC: antoine.zimmermann@insa-lyon.fr, semantic-web@w3.org
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
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
> <mailto: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
> <mailto:antoine.zimmermann@insa-lyon.fr>
> <mailto:antoine.zimmermann@insa-lyon.fr
> <mailto: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
> <mailto:antoine.zimmermann@insa-lyon.fr><mailto:
> antoine.zimmermann@insa-lyon.fr
> <mailto:antoine.zimmermann@insa-lyon.fr>>
>
> 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/
Received on Tuesday, 24 May 2011 05:55:11 UTC