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Name of a graph? and FROM and FROM NAMED

From: Yoshio FUKUSHIGE <fuku@w3.org>
Date: Thu, 2 Jun 2005 19:12:15 +0900
Message-ID: <004701c5675b$8d742090$f1e41b85@steelball>
To: <public-rdf-dawg@w3.org>

Hi,

# sorry for the length of this message

There are some points I found I didn't understand
w.r.t. FROM and FROM NAMED.

rq23(rev.1.367) says in  9.1
[[
The FROM clause a single URIs that indicates the graph to use as the default 
graph.
]]

I don't understand this.

(1) I can't find a verb.
(2) Does this "URIs" happen to be "URI"?
(3) Does this "the graph to use as" happen to be "the graph to be used as"?

#OK, the grammatical errors are not what I really point out

Even so, I don't understand.
Does this mean that the query issuer can replace the default graph by using 
a FROM clause?
(which I don't believe)
or is it the case
(3)' "the graph to use as" is really "the graph to be used as a part of"?

If so, then why is FROM clause restricted to appear once,
while FROM NAMED clause is allowed to be appear zero or more times. (A. 
[10,11] )
# if this was the thing discussed in the last telecon, sorry

And there continues
[[
This does not automatically put the graph in as a named graph;
]]

Well, I wonder what the "name of a graph" is...
It seems to be a URI a graph is given by the local system when read into the 
aggregator.
8.4
[[
 Each time a graph is read into the aggregator, it is given a URI by the 
local system.
]]
but, so it may not be the same URI the graph had BEFORE being aggregated,
which means we cannot know the name of a named graph without asking (but 
how?) !

It seems that a subgraph in the default graph can also have its name.
The example in 8.1 implies this. But isn't  that the URL where the subgraph 
was taken from?

It puzzles me. Does a copy of a graph has the same URI as the original one?
It seems to be No, then what we call "the name of a graph" is not given by 
the local system,
but it has been already given to the original graph

If so, then why a graph incorporated by FROM clause cannot be called (or 
named) by the URI
in that clause?

And what is the motivation of distinguishing FROM and FROM NAMED?

I remember FROM NAMED doesn't incorporate a graph to the default graph (but 
where in rq23?),
while FROM does so.

But does it mean FROM has a side effect to the default graph?

Best,
Yoshio
fukushige.yoshio@jp.panasonic.com
fuku@w3.org
Received on Thursday, 2 June 2005 10:12:16 GMT

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