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Re: Deduced property

From: Aidan Hogan <aidan.hogan@deri.org>
Date: Thu, 30 Jan 2014 15:42:11 -0300
Message-ID: <52EA9D03.3080501@deri.org>
To: Enrico Franconi <franconi@inf.unibz.it>
CC: PAUL WARREN <paul.w.warren@btinternet.com>, Dave Reynolds <dave.e.reynolds@gmail.com>, "semantic-web@w3.org" <semantic-web@w3.org>
On 30/01/2014 14:55, Enrico Franconi wrote:
>
> On 30 Jan 2014, at 16:29, Aidan Hogan <aidan.hogan@deri.org> wrote:
>
>> Paul, I think Dave's advice is sound: as tempting as it might be, it is *not* helpful to talk about OWL subsumption using phrases like inheritance. This will do more harm than good (esp. since the counter-examples will heavily outweigh the examples).
>
> Not really.
> "Inheritance" (in the object oriented sense) holds true in DL: a property of all the *objects* of a superclass is inherited to all the *objects* of the subclass.
> So, if class C is subsumed by class D, then if all the objects in class D have a property P, then all the objects in class C have the property P.
> This is true in Java, description logics, OWL, Smalltalk, CLOS, etc.

Yes but I think this is quite a jump away from the topic of the thread 
so far. We were discussing the (lack of) "inheritance" of transitivity 
in properties.

Your argument specifically relates to one feature of OWL: 
someValuesFrom. Indeed there's some notion of "inheritance" in an 
object-oriented sense here (as well as for the other property-based 
restrictions on classes). But again this is only a subset of the 
features of OWL (and not the ones we were discussing).

Some "features" of OWL are "inherited". Others are not.

a sCO b. b equivClass c . ⊬ a equivClass c .
a sPO b . b inverseOf c . ⊬ a inverseOf c .
a sPO b . b equivProp c . ⊬ a equivProp c .
a sPO b . b type SymProp . ⊬ a type SymProp .
a sPO b . b type TransProp . ⊬ a type TransProp .
...

... I still maintain my original point that it is *not* helpful to talk 
about OWL subsumption using phrases like inheritance. :)


Cheers,
Aidan

> cheers
> —e.
>
>
>>
>> Hence why the "inheritability" of different OWL features isn't documented (and nor should it be).
>>
>> If you want a non-technical means of introducing the features of OWL, examples using IF -- THEN -- (i.e., rules) will give a sound but incomplete picture. Studying the rules in OWL 2 RL/RDF is a great starting point for anyone wanting to learn a bit about what the *key* entailments of the OWL (2) features are (and without having to get into the formal semantics):
>>
>> http://www.w3.org/TR/owl2-profiles/#Reasoning_in_OWL_2_RL_and_RDF_Graphs_using_Rules
>>
>> The OWL features mean more than what's represented in these rules, but IF you can understand these rules, THEN you'll have a working knowledge of OWL.
>>
>> (Unfortunately though, I feel we're fighting a losing battle with regards the didactic aspects of OWL in the broader sense of it being a *Web standard*. Perhaps the battle is even already lost.)
>>
>> Best,
>> Aidan
>>
>>
>> On 30/01/2014 05:43, PAUL WARREN wrote:
>>> I have come across this problem recently in some work I have been doing
>>> investigating people's understanding of OWL constructs.  You can't
>>> assume that property characteristics are inherited - some are (e.g.
>>> functionality), some aren't (e.g. transitivity and symmetry).  But I
>>> have found no reference in any documentation to this fact.
>>>
>>> Cheers,
>>>
>>> Paul Warren
>>>
>>> ------------------------------------------------------------------------
>>> *From:* Dave Reynolds <dave.e.reynolds@gmail.com>
>>> *To:* semantic-web@w3.org
>>> *Sent:* Wednesday, 29 January 2014, 17:05
>>> *Subject:* Re: Deduced property
>>>
>>> OWL, and the underlying logic, are quite different from object oriented
>>> modelling so using terms like "inheritance" can trip you up. Especially
>>> when it comes to property axioms.
>>>
>>> In the RDF/OWL way of thinking then a property corresponds to set of
>>> pairs of things that are related by the property. So saying
>>>
>>>      :hasParent rdfs:subPropertyOf :hasAncestor
>>>
>>> means, and only means, that the set of pairs of things related by
>>> :hasParent is a subset of the set of pairs of things related by
>>> :hasAncestor.
>>>
>>> It's sets all the way down :)
>>>
>>> Dave
>>>
>>> On 29/01/14 16:47, Jean-Claude Moissinac wrote:
>>>> OK
>>>> I really thought that the transitivity was inherited. I will try to find
>>>> where and how the non-inheritance is specified
>>>> Thank you
>>>>
>>>> --
>>>> Jean-Claude Moissinac
>>>>
>>>>
>>>>
>>>> 2014-01-29 Matthew Horridge <matthew.horridge@stanford.edu
>>> <mailto:matthew.horridge@stanford.edu>
>>>> <mailto:matthew.horridge@stanford.edu
>>> <mailto:matthew.horridge@stanford.edu>>>
>>>>
>>>>     Hi Jean-Claude,
>>>>
>>>>     Asserting
>>>>
>>>>     :hasParent rdfs:subClassOf :hasAncestor
>>>>
>>>>     and
>>>>
>>>>     :hasAncestor rdf:type owl:TransitiveProperty
>>>>
>>>>     does not mean that :hasParent is also transitive.  Transitivity
>>>>     isn’t “inherited” down the property hierarchy, so it’s possible to
>>>>     have a non-transitive sub property of a transitive super property.
>>>>
>>>>     Cheers,
>>>>
>>>>     Matthew
>>>>
>>>>     On 29 Jan 2014, at 08:30, Jean-Claude Moissinac
>>>>     <jean-claude.moissinac@telecom-paristech.fr
>>> <mailto:jean-claude.moissinac@telecom-paristech.fr>
>>>>     <mailto:jean-claude.moissinac@telecom-paristech.fr
>>> <mailto:jean-claude.moissinac@telecom-paristech.fr>>> wrote:
>>>>
>>>>>     No, it's not the answer because hasAncestor is transitive and
>>>>>     hasParent isn't...
>>>>>     (I've a lot of similar situations)
>>>>>
>>>>>     --
>>>>>     Jean-Claude Moissinac
>>>>>
>>>>>
>>>>>
>>>>>     2014-01-29 Richard Cyganiak <richard@cyganiak.de
>>> <mailto:richard@cyganiak.de>
>>>>>     <mailto:richard@cyganiak.de <mailto:richard@cyganiak.de>>>
>>>>>
>>>>>         Jean-Claude,
>>>>>
>>>>>         You’re looking for this (in Turtle syntax):
>>>>>
>>>>>           :hasParent rdfs:subClassOf :hasAncestor.
>>>>>
>>>>>         (Don’t try to read or write RDF/XML directly. You’ll go mad.
>>>>>         Use the friendly syntaxes such as Turtle, or graphical tools.)
>>>>>
>>>>>         Best,
>>>>>         Richard
>>>>>
>>>>>
>>>>>         On 29 Jan 2014, at 16:18, Jean-Claude Moissinac
>>>>>         <jean-claude.moissinac@telecom-paristech.fr
>>> <mailto:jean-claude.moissinac@telecom-paristech.fr>
>>>>>         <mailto:jean-claude.moissinac@telecom-paristech.fr
>>> <mailto:jean-claude.moissinac@telecom-paristech.fr>>> wrote:
>>>>>
>>>>>         > Sorry if my question is very naive, but I'm stuck on this
>>>>>         for a while
>>>>>         > if I go to examples in the document
>>>>> http://www.w3.org/TR/2009/WD-owl2-primer-20090421/
>>>>>         > I just want to add the following axiom (expressed here in my
>>>>>         syntax)
>>>>>         > if
>>>>>         > ?s :hasParent  ?f
>>>>>         > Then
>>>>>         > ?s :hasAncestor ?f
>>>>>         >
>>>>>         > I've checked a lot of documents and I don't figure how to do
>>>>>         it (directly in XML/RDF or interactively with Protégé)
>>>>>         >
>>>>>         > Thank you in adavnace for your help
>>>>>         >
>>>>>         > --
>>>>>         > Jean-Claude
>>>>>         >
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>
Received on Thursday, 30 January 2014 18:42:36 UTC

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