Re: Publications about OWL (1 or 2) Full

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.

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.

Thanks again,
Michael

On Thu, May 19, 2011 at 12:25 PM, Michael F Uschold <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> 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>> 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/
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>> --
>> 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
>
>


-- 
Michael Uschold, PhD
   Senior Ontology Consultant, Semantic Arts
   LinkedIn: http://tr.im/limfu
   Skype, Twitter: UscholdM