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RE: motivation for bNodes/existentials in RDF; note for parsers

From: Massimo Marchiori <massimo@w3.org>
Date: Mon, 25 Mar 2002 18:22:27 +0100
To: "Jan Grant" <Jan.Grant@bristol.ac.uk>
Cc: "Dan Connolly" <connolly@w3.org>, "Pat Hayes" <phayes@ai.uwf.edu>, "w3c-rdfcore-wg" <w3c-rdfcore-wg@w3.org>, "Lynn AndreaStein" <las@olin.edu>
> > So, summing up, since this is a fundamental architectural decision
> > (not just syntactic sugaring) concerning RDF, what is most interesting
> > is to give the reasons for this interpretation vs the easiest
> skolem one.
> > Yes, it's a classic "last call" fundamental question, because
> that spawns
> > into the data model, on which there are many things to discuss,
> but well,
> > Dan brought the matter up early ;)
> At the first WG F2F we had a long (and, i think, productive) argument*
> about this. Sergei produced a good set of pros and cons; my arguments
> for this are ...
> - supports "non-assertional" mode, ie, RDF querying by turning around
>   the "X entails what?" into "what entails X?"
> - aesthetic reasons, and those of transparency. When I write an
>   assertion with a blank node, I intend it to mean "there exists...".
> - DanC also claimed that skolemisation was too much of a general
>   impediment to getting software written :-) I think he may have
>   been dramatising for, well, dramatic effect, but I've some sympathy
>   with this POV. In other words, supporting anonymous nodes requires
>   some API fiddling, but is not necessarily a "simpler mechanism".

Thanks for the initial reply, Jan.
I don't want to start a complex debate without first having seen a complete
reply, just noticing that this is such a fundamental architectural decision
that a complete and careful pro/con analysis is due. The above three "pro"
all have good counterarguments, so I'll wait to see for the full official
motivation-and-reasoning behind such a milestone decision.


> * debate may not be too kind a word. It was certianly heated!
I can well imagine... ;)
Received on Monday, 25 March 2002 12:23:21 UTC

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