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Re: Deduced property

From: Pavel Klinov <pavel.klinov@uni-ulm.de>
Date: Fri, 31 Jan 2014 12:44:32 +0100
Message-ID: <CAG5JQxXQkHdGrJQs+8xu8OpfxpBNqf2vFYuvs0wZ5rb8h_0fpg@mail.gmail.com>
To: PAUL WARREN <paul.w.warren@btinternet.com>
Cc: Aidan Hogan <aidan.hogan@deri.org>, Enrico Franconi <franconi@inf.unibz.it>, Dave Reynolds <dave.e.reynolds@gmail.com>, "semantic-web@w3.org" <semantic-web@w3.org>
On Fri, Jan 31, 2014 at 11:38 AM, PAUL WARREN
<paul.w.warren@btinternet.com> wrote:
> I think the issue is more fundamental than the use of the word
> 'inheritance'.  In a recent trial I found that eight out of 12 participants
> assumed that if a property is transitive, then so is its subproperty.  This
> was despite the fact that the participants were computer scientists, with
> some knowledge of ontologies, and that introductory reading before the trial
> pointed out that this was not the case.
>
> I suggest the problem is with the syllable 'sub', as in subproperty.  Most
> computer scientists will assume inheritance when they see 'sub' (whether
> they use the actual word 'inheritance' or not).  This will be the case
> whether they come from an OO background, or whether they are used to
> thinking about subclasses in ontologies.  As has been pointed out,
> properties and their restrictions are inherited by subclasses.
>
> I am simply saying that this needs to be made more explicit in teaching
> about ontologies.  It's probably too late now, but a different term from
> subproperties, e.g. 'property specializations', would be useful.

I do not agree with this. There's no difference between the semantics
of subclasses and subproperties. A class is interpreted as a set of
objects. A property is interpreted as a set of pairs. A subclass is
interpreted as a subset of the interpretation of the superclass. A
subproperty is interpreted as a subset of the interpretation of the
superproperty. They really do behave the same. If something is true
for *every* pair of objects related by R, it will be true for *every*
pair of objects related by a subproperty of R. Precisely as for
subclasses.

The problem is here: "As has been pointed out, properties and their
restrictions are inherited by subclasses". This is not really what has
been pointed out.

Cheers,

Pavel

>
> Cheers,
>
> Paul Warren
>
> ________________________________
> From: Aidan Hogan <aidan.hogan@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>
> Sent: Thursday, 30 January 2014, 18:42
> Subject: Re: Deduced property
>
> 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 Friday, 31 January 2014 11:45:03 UTC

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