- From: Antoine Zimmermann <antoine.zimmermann@insa-lyon.fr>
- Date: Thu, 19 May 2011 19:58:59 +0200
- CC: Semantic Web <semantic-web@w3.org>
First, thanks to you Michael and Markus for your replies. Now, Michael, Le 19/05/2011 19:42, Michael F Uschold a écrit : > Thanks for a thorough reply. See comments inline. > > On Thu, May 19, 2011 at 3:09 AM, Markus Krötzsch< > markus.kroetzsch@comlab.ox.ac.uk> wrote: > >> On 18/05/11 19:49, Michael F Uschold wrote: >> >>> These are good questions. You are right, the current attitude and >>> practice is avoid OWL Full at all costs. Unfortunately, this ignores >>> the costs of NOT using OWL Full -- basically it means having to do a lot >>> of painful workarounds that make the ontology harder to understand which >>> undermines one of the key goals of ontology: to make meaning clear! >>> >>> If you want to be able to have meta classes, and use classes as values >>> for properties and other OWL Full goodies, you have to use a more >>> powerful reasoner. Any FOL prover would do, I should think, but I am no >>> expert. >>> >> >> 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. > > 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 . } > > 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? > > >> 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. Regards, AZ. >> >> 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>> 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> - >>> Fax: +33(0)4 72 43 87 13<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> >>> >>> 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 http://korrekt.org/ >> > > > -- 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 - Fax: +33(0)4 72 43 87 13 Lecturer at: Institut National des Sciences Appliquées de Lyon 20 Avenue Albert Einstein 69621 Villeurbanne Cedex France antoine.zimmermann@insa-lyon.fr http://zimmer.aprilfoolsreview.com/
Received on Thursday, 19 May 2011 17:59:30 UTC