RE: OWL Web Ontology Language

Hi Peter,

At the risk of becoming a nuisance I want to ask you for some further
clarifications. Please see below.

Regards,
Hans 

-----Original Message-----
From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com] 
Sent: Friday, March 17, 2006 17:40
To: hans.teijgeler@quicknet.nl
Cc: semantic-web@w3.org
Subject: Re: OWL Web Ontology Language

From: "Hans Teijgeler" <hans.teijgeler@quicknet.nl>
Subject: RE: OWL Web Ontology Language
Date: Thu, 16 Mar 2006 23:27:39 +0100

> Hi Peter,

=======================================================
[HT1] 
> What do you understand when someone tells you that Ford produces 
> Mustangs? They produce also other models, they may or may not 
> outsource all or part (most "US" products come from China), but one 
> thing is certain: Ford produces Mustangs, one way or the other.

[PFPS1]
Well, is Ford the *only* manufacturer of Mustangs?  If all you want to say
is that Ford produces some Mustangs, then you probably want

	ObjectProperty(manufactures inverseOf(manufactured-by))

	Individual(Ford value(manufactures(Individual(type(Mustang)))))

Or if you want to say that Ford *might* produce some Mustangs, then you
probably want 
 
[Yes, I did mean to say nothing here.]

[HT2]  
When I read this well you state that Ford manufactures A Mustang, not many
Mustangs. Ford manufactures members of the class Mustang, has done so and
will do so, and in this context it is unimportant whether others do as well.

[PFPS2]


========================================================

[HT1]
> Forgive me my ignorance: what do you mean with 'partial'? I scanned 
> through the W3C Recommendations but could not find it.

[PFPS1]
Here is an extract from OWL S&AS on 'partial':

>>>>>>>>>>>>>>>>>>>>>>>>>>>
2.3.1. OWL Lite Axioms
2.3.1.1. OWL Lite Class Axioms
 
In OWL Lite class axioms are used to state that a class is exactly
equivalent to, for the modality complete, or a subclass of, for the modality
partial, the conjunction of a collection of superclasses and OWL Lite
Restrictions. It is also possible to indicate that the use of a class is
deprecated. 

axiom ::= 'Class(' classID ['Deprecated'] modality { annotation } { super }
')'
modality ::= 'complete' | 'partial'

[...]

2.3.2. OWL DL Axioms
2.3.2.1. OWL DL Class Axioms

The OWL DL abstract syntax has more-general versions of the OWL Lite class
axioms where superclasses, more-general restrictions, and boolean
combinations of these are allowed. Together, these constructs are called
descriptions. 

axiom ::= 'Class(' classID  ['Deprecated'] modality { annotation } {
description } ')'
modality ::= 'complete' | 'partial'
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

[HT2]
In the W3C Recommendation on RDF Schema the understanding of RDF Semantics
was called "daunting". The understanding of OWL S&AS to me is daunting as
well. I am simply not clever enough for that. So please help me a bit.

I think I understand:
	axiom ::= 'Class(' classID ['Deprecated'] modality { annotation } {
super } ')'
	modality ::= 'complete' | 'partial'
	super ::= classID | restriction

But then what does "Class(Manufacturer partial)", mentioned below, exactly
mean? And what "Class(Car partial)" and "Class(Mustang partial Car
restriction(manufactured-by value(Ford)))" ? And how does it prove your
point?

[PFPS2]


=========================================================

[HT1]
> The code you show may not be correct, but I accept that you know more 
> of OWL than I do. The rdf:range of someValuesFrom is rdfs:Class, and 
> Ford is an Individual. How do you match that?

[PFPS1]
Oops, I made an error.  I should have said


	Class(Manufacturer partial)
	Individual(Ford type(Manufacturer))

	ObjectProperty(manufactured-by Functional)

	Class(Car partial)

	Class(Mustang partial Car restriction(manufactured-by value(Ford)))

[HT2]
The way I read owl:FunctionalProperty is that the rdf:range of the Property
typed as FunctionalProperty can only have one value. That is fine, but that
rdf:object can only be a Class, and not an individual. Right?
In the past I have suggested to create, as a work-around, a singleton class
for this purpose, i.e. we create a Class 'Ford', of which 'Ford' is, by
definition, the only member. But it seems that OWL does not have a legal way
to declare singleton classes.

[PFPS2]


=========================================================

> Regards,
> 
> Hans


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Received on Friday, 17 March 2006 18:50:54 UTC