RE: Inheritance and RIF

Hi Yuzhong,

Your reference to "XML Schema Datatypes in RDF" is VERY useful. Thanks!

Regards,
Hans

-----Original Message-----
From: Yuzhong Qu [mailto:yzqu@seu.edu.cn] 
Sent: Monday, April 03, 2006 2:38
To: hans.teijgeler@quicknet.nl; Peter F. Patel-Schneider
Cc: semantic-web@w3.org; aginsberg@imc.mitre.org
Subject: Re: Inheritance and RIF

Hi, Hans,

In addition to Peter's comment, a possibel solution (practically) to your
question is as follows:

// About knowledge modeling
weight is a owl:DatatypeProperty with xsd:postiveInteger (or xsd:decimal, if
you like) as its rdfs:range; weight is also a owl:FunctionalProperty. (if
the tense issue is ignored)

Lightweight is a user-defined XML Schema Datatype, e.g. ranging from 130
to135.  
[See "XML Schema Datatypes in RDF",
http://www.w3.org/TR/swbp-xsch-datatypes/ , for details on defining your own
datatypes ]

LightweightBoxer is a subClassOf  Boxer and also be restricted to
Lightweight w.r.t. the weight property.

// About usage
When you assert that John Doe is a 'lightweight boxer', the weight of John
Doe must be "a value" between 130 and135. 


Yuzhong Qu
 
----- Original Message -----
From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
To: <hans.teijgeler@quicknet.nl>
Cc: <semantic-web@w3.org>; <aginsberg@imc.mitre.org>
Sent: Monday, April 03, 2006 5:05 AM
Subject: Re: Inheritance and RIF


> 
> From: "Hans Teijgeler" <hans.teijgeler@quicknet.nl>
> Subject: Inheritance and RIF
> Date: Sun, 2 Apr 2006 21:58:50 +0200
> 
>> Folks,
>>  
>> I looked for the word "inheritance" in the W3C website, but didn't find
>> what I was looking for.
>>  
>> Assume we have a class called 'lightweight boxer'.
>> The "criteria for membership" for that class are, amongst others, that
>> the weight of any male boxer of that class, right before a match, shall
>> be between 130 and 135 lbs. So I may introduce the Properties minWeight
>> and maxWeight, with these values.
> 
> Hmm, well, here you are making one of the standard modelling choices that
> can lead to problems.  
> 
> Note well that the meaning of the "properties" minWeight and maxWeight are
> very different from the property weight.  The former two are, perhaps,
> properties of the class whereas the latter one is a property of instances
> of the class.
> 
>> Now I have John Doe, and I type him as 'lightweight boxer'. 
>>  
>> Are now the minWeight and maxWeight Properties inherited, even where
>> these are meaningless for a person? (because an individual doesn't have,
>> at any given point in time, a range value, but a point value)
> 
> And here is where your modelling choice bites you.
> 
>> Or is inheritance only a function that software (reasoners and the like)
>> must handle? 
> 
> Well, "inheritance" is, at best, a description of what goes on in some
> relationships between classes and their instances, or classes and their
> subclasses.  It is far better to think logically, i.e., *what* follows (or
> should follow) instead of *how* to make it follow.
> 
>> Will RIF become a suitable mechanism for that? In this case we would
>> need a function that looks at the weight of John Doe and checks whether
>> or not that is between minWeight and maxWeight, and if yes confirms that
>> the asserted typing was correct, or would even generate that typing (of
>> course including other ciriteria, otherwise we would have zillions of
>> lightweight boxers in the world).
> 
> Well, RIF shouldn't have any mechanism for inheritance.   After all, RIF
is
> not about classes and instances, but is instead about rules.
> 
>> By the way: does anyone know how to represent a value with a tolerance
>> in RDF/OWL? So something like: diameter = 150 mm +0.03%  -0.25%.
>>  
>> Regards,
>> Hans
> 
> My suggestion to you would be to read the KR literature, where this entire
> issue was discussed at length.  A good starting point would be 
> 
> title= "What's in a Link:
> Foundations for Semantic Networks",
> author= "Woods, William A.",
> pages= "35--82",
> booktitle= "Representation and Understanding:
> Studies in Cognitive Science",
> editor= "Daniel G. Bobrow and Alan M. Collins",
> year= 1975,
> publisher= "Academic Press",
> 
> This paper also appears in:
> 
> editor= {Ronald J. Brachman Hector J. Levesque},
> title= "Readings in Knowledge Representation and Reasoning",
> booktitle= "Readings in Knowledge Representation and Reasoning",
> publisher= "Morgan Kaufmann",
> address= "San Mateo, California",
> year= 1985,
> 
> 
> Another good paper to read would be:
> 
> title= "What's in a Concept: 
> Structural Foundations for Semantic Networks",
> author= "Brachman, Ronald J.",
> journal= "International Journal of Man-Machine Studies",
> volume= 9,
> number= 2,
> month= mar,
> year= 1977,
> 
> 
> Peter F. Patel-Schneider
> Bell Labs Research
> 
> 
>

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Received on Monday, 3 April 2006 07:30:17 UTC