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Re: Streaming version of CONSTRUCT

From: Bob MacGregor <bmacgregor@siderean.com>
Date: Mon, 21 Feb 2005 15:26:08 -0800
Message-ID: <421A6E10.9060309@siderean.com>
To: andy.seaborne@hp.com
CC: public-rdf-dawg@w3.org

Andy,

Seaborne, Andy wrote:

> ... snip ...
>
> To quote the current working draft:
>
> """
> CONSTRUCT with a template
> ...
> If any such instantiation produces a triple containing an unbound 
> variable, or an illegal RDF construct (such as a literal in subject or 
> predicate position) then that triple is not included in the RDF graph
> """
>
> Only the triple involved, not the whole template, is skipped on 
> unbound variables.
>
>     Andy

I did read through it quickly, but you left out the part about the 
optional warning.

   "then that triple is not included in the RDF graph, and a warning may 
be generated."

It would be very annoying (and just plain wrong) to generate a warning if
an unbound variable occurred in a template when it is sanctioned by an
OPTIONAL within a WHERE clause.   Perhaps the spec should be rewritten to
say something like:

   "an unbound variable prevents the inclusion of the enclosing triple 
in the RDF graph, while
an illegal construct (such as ...) also prevents the inclusion of a 
triple and may
generate a warning"

So, given that unbound variables ARE OK (modulo spurious warnings) in a 
template,
I fail to see why you had a problem representing trees with variable 
depth -- perhaps
some other kind of variability is a problem, but templates can easily 
generate trees
with different depths.

Cheers, Bob
Received on Monday, 21 February 2005 23:27:50 GMT

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