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Subject: RE: [xdi] XDI addresser & Xref subsegments
I thought an xref contained XRI had to begin with a GCS?
i.e. (+old) not (old).
From: Drummond Reed Sent: Sat 1/17/2009 5:12 PM To: 'Markus Sabadello' Cc: 'Giovanni Bartolomeo'; 'OASIS - XDI TC' Subject: [xdi] XDI addresser & Xref subsegments Markus, nice enhancement to XDI Addresser. BTW, I checked to see if it supports xref delimiters yet and it appears it doesn’t. I did a get on =markus/+friend(old) against the graph =giovanni +name "Giovanni B" +friend =bill =drummond =markus =markus +friend =giovanni +friend(old) =drummond +name "Markus S" +test / =subj1 +pred1 +ref1 +ref2 +pred2 "literal" and got the error Unknown serialization format. Probably just a library update since you indicated you already have the XDI4J parser supporting xref delimiters. =Drummond From: markus.sabadello@gmail.com [mailto:markus.sabadello@gmail.com] On Behalf Of Markus Sabadello This summary is very useful. On Sat, Jan 17, 2009 at 4:18 AM, Drummond Reed <drummond.reed@cordance.net> wrote: Giovanni, I'm cleaning up some emails in the past week that that I never answered. This one had two questions from you, which I'll just answer up front since the thread was getting pretty deep (and it also answers a question pending from Markus too). The first one was "what does +a+b+c infer?" I think this is now answered by the $has section of http://wiki.oasis-open.org/xdi/XdiOne/RdfGraphModel and by diagrams 3A, 3B, 3C, and 3D of http://www.oasis-open.org/committees/download.php/30719/xdi-rdf-graph-model-diagrams-v2.pdf. Please look these over and let me know if you still have issues. The second one was a suggestion about Markus' question about addressing predicates (arcs). You suggested that maybe all addresses in the graph were actually arcs. I investigated that path once about two years ago but realized that while all the identifiers are arcs, the arc itself is not what is identified by the arc. What the arc identifies is the node to which it points. But it is important to mention that the XDI RDF graph does have the ability to address a set of arcs identifing a set of nodes, not just one node. We do this by allowing XDI addresses that consist of {subject}/{predicate} and no object. In fact you can draw the following table based on XDI address forms: {subject} <== addresses exactly one node if true {subject}/{predicate} <== addresses 1-n nodes if true {subject}/{predicate}/{object} <== addresses exactly one node if true {subject}/{predicate}// <== addresses 1-n nodes (a context) if true So {subject}/{predicate} and {subject}/{predicate}// are both ways to address a set of n>= 1 nodes in the graph. Hope this helps, =Drummond From: Giovanni Bartolomeo [mailto:giovanni.bartolomeo@uniroma2.it]
Subject: More comments on XDI metagraph predicate examples (was: RE: [xdi] Minutes: XDI TC Telecon Thursday 1-2PM PT 2008-12-18) Hello Drummond, At 09.09 30/12/2008, Drummond Reed wrote: [giovanni] To further clarify, I also propose to have
+a/$has/+b+c ==> +a+b+c +a+b/$has/+c ==> +a+b+c
however, if you want to REVERSE these statements, starting from +a+b+c, you can infer EITHER (1) +a/$has/+b+c OR (2) +a+b/$has/+c OR (3) both. And the outcomes are different in the three different cases. [giovanni] In example #8 (equivalence +x/$is/+y) the arc connecting the two circles is labelled with +y, does it have a particular meaning? Maybe, for consistency's sake, it is better to maintain the graphical convention to name the arc after the predicate. Since $is is a symmetric predicate, what do you think about the following amendment?
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