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Re: The semantics of blank nodes

From: <MDaconta@aol.com>
Date: Wed, 13 Nov 2002 13:44:56 EST
Message-ID: <54.22248b4.2b03f7a8@aol.com>
To: jon@spin.ie, www-rdf-interest@w3.org
In a message dated 11/13/2002 9:34:17 AM US Mountain Standard Time, 
jon@spin.ie writes:

> 1. You simply may not know (or have a vocabulary to express) the type.
> 2. You simply may not have a useful identifier.

I agree that there are valid use cases for blank nodes.

> You can still make use of what you do know though.
> The semantics of a blank node convey certain information, and do so in a
> manner compatible with statements not using blank nodes. Only if they 
> failed
> to do that could you say that the semantics were weakened.

I don't agree with that.  You can certainly compare the semantics
of different data representations just as people compare the semantic
expressiveness of RDF to XML Schema.  I also believe it is intuitive that a 
typed blank node provides better semantics than an untyped blank
node.  In terms of best practice, is it not better to avoid using a 
blank node if possible?

> Of course in the example:
> <http://www.example.org/staffid/85740>
> <http://www.example.org/terms/address>
> _:johnaddress .
> _:johnaddress
> <http://www.example.org/terms/street>
> "1501 Grant Avenue" .
> It could perhaps be possible to add a type (perhaps from knowing the range
> of <http://www.example.org/terms/address>, perhaps from elsewhere) and/or a
> URI (perhaps from an unambiguous predicate). So even if your application
> required the type or URI the above triples wouldn't necessarily be useless
> once they have been merged with others.


 - Mike
Michael C. Daconta
Director, Web & Technology Services
Received on Wednesday, 13 November 2002 13:45:49 UTC

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