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Re: Deduced property

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Thu, 30 Jan 2014 18:55:45 +0100
CC: PAUL WARREN <paul.w.warren@btinternet.com>, Dave Reynolds <dave.e.reynolds@gmail.com>, "semantic-web@w3.org" <semantic-web@w3.org>
Message-ID: <0ED33819-0966-42B6-BDBE-87133270AB1B@inf.unibz.it>
To: Aidan Hogan <aidan.hogan@deri.org>

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.
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 17:56:18 UTC

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