From: Giovanni
Bartolomeo [mailto:giovanni.bartolomeo@uniroma2.it]
Sent: Thursday, March 13, 2008
3:11 AM
To: Drummond Reed; 'Markus
Sabadello'
Cc: barnhill_william@bah.com;
xdi@lists.oasis-open.org
Subject: RE: [xdi] Groups - XDI
RDF v8 Comments-Barnhill (pdf) (XDI RDF v8 Comments-Barnhill.pdf) uploaded
Hello Drummond,
Thanks for this clarification; however, if my understanding is correct, this
means that an XDI document can also be subject of another XDI document, other
than object.
Doesn't this implies that we should update ABNF syntax making the definition of
subject somehow similar to the one for object?
X3
= *( "[" sub *( "[" pred *( "[" obj "]"
) "]" ) "]" )
sub = [ comment ] xri-reference [ comment ]
sub = [ comment ] (xri-reference / X3) [ comment ]
pred = [ comment ] xri [ comment ]
obj = [ comment ] ( xri-reference / literal / X3 ) [ comment ]
literal = """ *char """
comment = "<--" *c-char "-->"
Further questions are:
should allow
literals as a subject?
should be
predicate definition similar to subject and object one update, e.g. may a
predicate contain an XDI document?
however I'm not quite convinced with these last two ideas... comments welcome!
Giovanni
At 22.38 12/03/2008, Drummond Reed wrote:
Just to be clear, the
“n-segment” syntax was deprecated in the V9 XDI RDF Model document
(
http://wiki.oasis-open.org/xdi/XdiRdfModel) due to the problems identified
in this thread. To be precise, it was unclear whether
s1
p1
o1
p2
o2
meant that s1/p1/o1 was the subject of p2/o2 or not. It was also unclear how
cross-reference syntax would be applied.
We solved both problems by eliminating “n-segment” syntax in the V9
document. Now it should be unambiguous that if you want to express that
s1/p1/o1 is the subject of p2/o2, you say:
(s1/p1/o1)/p2/o2
What did remain is the // syntax for subcontexts, which allows you to solve the
RDF “blank node problem” by providing an address for a blank node.
That address is simply // (which fits very nicely from a conceptual standpoint
since the identifier for that segment is “blank”).
So if I want to say that the object of s1/p1 is a blank node, I can write it as
s1/p1// . This creates a new XDI context in which I can express another set of
XDI statements whose XRIs are unique in this context.
We’ll go over the practical uses for this on the call tomorrow –
agenda coming out shortly.
=Drummond
From:
markus.sabadello@gmail.com [ mailto:markus.sabadello@gmail.com] On Behalf Of Markus Sabadello
Sent: Wednesday, March 12, 2008
10:44 AM
To: Giovanni Bartolomeo
Cc: barnhill_william@bah.com;
xdi@lists.oasis-open.org
Subject: Re: [xdi] Groups - XDI
RDF v8 Comments-Barnhill (pdf) (XDI RDF v8 Comments-Barnhill.pdf) uploaded
To be honest, I don't really understand the N-Segment syntax anyway.
Why is
s1
p1
o1
p2
o2
better than
s1
p1
o1
o1
p2
o2
?
Markus
On Tue, Mar 11, 2008 at 4:29 PM, Giovanni Bartolomeo < giovanni.bartolomeo@uniroma2.it>
wrote:
Dear Bill, All,
reading your comments about XDI RDF v8 ( http://www.oasis-open.org/committees/download.php/27112/XDI%20RDF%20v8%20Comments-Barnhill.pdf
) I've found this sentence:
One problem with the
3-Segment syntax is that the N-Segment syntax uses cross-references for
reification. This means 3-Segment syntax has to have a different notation for a
subject which is the
statement itself rather than the object of the statement. The 3-Segment
notation for this is a crossreference
within a cross-reference: (()). So a subject of (s/p/o) asserts s/p/o and
starts a new statement
whose subject is o, while a subject of ((s/p/o)) asserts s/p/o and starts a new
statement whose subject is
the statement s/p/o. For example to say that =Drummond is author of the
statement =Bill.Barnhill is a
contributor to the resource represented by @example we would use the XRI:
((@example/+dc+contributor/=Bill.Barnhill))/+dc+author/=Drummond.
Well, I'm wondering how N3 syntax (and consequently X3 simple)
addresses this problem:
If my understanding is correct, the N3 syntaxt
<s1> <p1>
<o1>
<o1> <p2> <o2>
is equivalent to X3 simple
s1
p1
o1
p2
o2
what if I want to express that the whole statement <s1>
<p1> <o1> is the subject of <p2> <o2>? How this can be
represented with X3 Simple?
Breaking into a new subcontext doesn't seem to help, as this explicitly
introduce a new subject!
s1
p1
/
s2
p2
o2
Whereas I just want that the whole statement (s1/p1/o1) is the subject of p2!
What do you think? Am I missing something?
Thanks,
Giovanni
At 11.06 07/02/2008, barnhill_william@bah.com
wrote:
The document named XDI RDF v8 Comments-Barnhill (pdf) (XDI RDF v8
Comments-Barnhill.pdf) has been submitted by Mr. William Barnhill to the OASIS
XRI Data Interchange (XDI) TC document repository. Document Description: View
Document Details: http://www.oasis-open.org/apps/org/workgroup/xdi/document.php?document_id=27112
Download Document: http://www.oasis-open.org/apps/org/workgroup/xdi/download.php/27112/XDI%20RDF%20v8%20Comments-Barnhill.pdf
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