RE: Deduced property

Hi,

(Also speaking from the sidelines, so apologies if this is nonsense).

As a software engineer, the striking difference is this.  In Java, if a class A  has property x, then all objects of that class have property x. If class B extends A, then all objects of class B also have property x.

In OWL the logical direction  is completely different. In OWL, if property x has domain A, that does NOT mean that all objects of class A have property x. It means that IF an object has property x, it must belong to class A (very roughly speaking -  I am aiming for conceptual intuition of the difference here, rather than strict accuracy). IF B is a subclass of A, and IF I can deduce that object b is a B, then it must also be an A.

Inheritance in programming languages allows one to deduce properties of an object  from a description of a class.  In OWL, the idea is to deduce the class of an object from a description of its properties.

The OWL specs do not talk about inheritance because inheritance in the usual sense does not apply to OWL. Other people believe that OWL has something to do with inheritance because the terminology of classes and subclasses is the same. But the meaning is quite different.

Tim.

From: Timothy W. Cook [mailto:tim@mlhim.org]
Sent: 31 January 2014 15:41
To: Aidan Hogan
Cc: Pavel Klinov; Enrico Franconi; PAUL WARREN; Dave Reynolds; semantic-web@w3.org
Subject: Re: Deduced property


On Fri, Jan 31, 2014 at 1:12 PM, Aidan Hogan <aidan.hogan@deri.org<mailto:aidan.hogan@deri.org>> wrote:

+1 ... and yep, I still maintain my original point that it is *not* helpful to talk about OWL subsumption using phrases like inheritance. :)
Speaking from the sidelines, but with a lot of experience in dealing with people from multiple domains and many perspectives.

It may not be helpful to talk about it in the specs.  But anytime you see that there is confusion over an topic from a segment of people that that is interested in and has a possible use for what you are producing/teaching.  Then you would benefit from talking about it in clarifying, informal documents; in a context that they are familiar with using.  In this case, 'inheritance' is a word used and understood by computer scientists.  If you use that as a starting point and then say what is different in 'OWL subsumption'; you will be a lot more successful in making your points.

HTH,
Tim






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