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Re: Some thoughts on the semantics of domain and range (was: Re: RDFS bug "A property can have at most one range property")

From: Natalya Fridman Noy <noy@SMI.Stanford.EDU>
Date: Fri, 15 Sep 2000 16:56:32 -0700
Message-Id: <4.2.0.58.20000915164044.00b6f3b0@smi.stanford.edu>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-interest@w3.org
At 05:07 PM 9/15/00 -0400, Peter F. Patel-Schneider wrote:
>From: Natalya Fridman Noy <noy@SMI.Stanford.EDU>
>Subject: Re: Some thoughts on the semantics of domain and range 
>(was:   Re: RDFS    bug "A property can have at most one range property")
>Date: Wed, 13 Sep 2000 16:28:10 -0700
> >
> > In fact, OKBC adopted the disjunctive semantics for domains and ranges of
> > slots (perhaps, for practical reasons), and it seemed to work well there.
> >
> > Natasha
>
>I don't see where OKBC did adopt the disjunctive semantics for this.  In
>fact, on page 16 of Open Knowledge Base Connectivity 2.0.3 (Proposed),
>which is the most recent document I could find, there is the statement:
>
>         Note that if slot :DOMAIN of a slot S has multiple values C1,...,Cn
>         then the domain of slot S is constrained to be the intersection of
>         classes C1,...,Cn.
>
>which indicates to me that OKBC using the conjunctive semantics for domains
>of slots.

Actually, OKBC allows both, disjunctive and conjunctive semantics. Right 
above the paragraph you cite on page 16, there is another one:

         A value for slot :DOMAIN can be a KIF expression of the following 
form:
                 <domain-expr> ::= (union <OKBC-class>*) | OKBC-class

The same is true for :VALUE-TYPE (that is, range) where the specs elaborate 
(p.12):

         The union expression allows the specification of a disjunction of 
classes (e.g., either a dog or a cat).

Natasha
Received on Friday, 15 September 2000 19:56:35 GMT

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