- From: Alan Ruttenberg <alanruttenberg@gmail.com>
- Date: Sun, 17 Mar 2013 00:51:08 -0400
- To: Erich Gombocz <egombocz@io-informatics.com>
- Cc: Jim McCusker <mccusj@rpi.edu>, David Booth <david@dbooth.org>, Jeremy J Carroll <jjc@syapse.com>, Umutcan ŞİMŞEK <s.umutcan@gmail.com>, Kingsley Idehen <kidehen@openlinksw.com>, w3c semweb HCLS <public-semweb-lifesci@w3.org>
- Message-ID: <CAFKQJ8nzF2q8EMRuS3JormvoVvJiiyRYGuuN93LBaUWmgBCDmA@mail.gmail.com>
My dad's name is Danny. I've known him a Long time, during which he's changed a lot. Am I supposed to stop calling him dad because he's not precisely the same as he was when I was 10? -Alan On Sunday, March 17, 2013, Erich Gombocz wrote: > Observing this discussions for quite a while, I have to say that I fully > agree with Jim’s comments - unless you can assert that the referent is > the same AND the contextual scope is the same, it should not have the same > URI as it does not *precisely *describe the same thing.**** > > ** ** > > Cordially,**** > > Erich**** > > ** ** > > *From:* Jim McCusker [mailto:mccusj@rpi.edu] > *Sent:* Saturday, March 16, 2013 9:35 PM > *To:* David Booth > *Cc:* Jeremy J Carroll; Umutcan ŞİMŞEK; Kingsley Idehen; w3c semweb HCLS > *Subject:* Re: owl:sameAs - Is it used in a right way?**** > > ** ** > > Hmm. In the end, all three of them are talking about the same apple. > Either a) the apple changed (they do that), or b) someone got it wrong (Is > a McIntosh a red apple or green apple? It's kind of both).**** > > ** ** > > This of course goes to my general assertion that most of the time, > disjointness assertions are more likely to be wrong than right, but this > isn't about that. There is an apple, and all three people agree they are > talking about the same apple. It may have changed, or someone was color > blind, or looking at a colorized black and white photo when they decided > what color it was. This is, more than anything, why, unless you know that > the referent is that same AND the contextual scope is the same, it's better > to mint your own URI and link out using altOf and specOf, rather than > making assertions using someone else's resource.**** > > ** ** > > Jim**** > > ** ** > > On Sun, Mar 17, 2013 at 12:20 AM, David Booth <david@dbooth.org> wrote:*** > * > > Hi Jim,**** > > > > On 03/16/2013 12:37 PM, Jim McCusker wrote:**** > > I'm not terribly interested in a Humpty Dumpty interpretation of the web > of data.**** > > ** ** > > Well, you'd better get used to it, because that interpretation is standard > RDF Semantics. I don't think it's going away any time soon.**** > > ** ** > > That's part of the motivation for having global identifiers > like URIs/URLs.**** > > ** ** > > Exactly! That's why the idea that "a URI identifies one resource" is "a > good goal, and helpful as a guide to URI users", even though it is not > actually true.**** > > ** ** > > There's no point in merging ANY graphs under this view, > since you have no way of knowing if the referents are the same.**** > > ** ** > > Not true! Don't throw the baby out with the bath. When you merge graphs, > you force the referents to be the same. Sometimes the merge works fine, and > sometimes the merge becomes inconsistent. Just because you cannot *always* > merge two graphs without causing inconsistency does not mean that merging > is pointless. It just means that *some* graphs can be merged and others > cannot. That is only a problem if your expectations of being able to merge > any two graphs are set unrealistically high.**** > > ** ** > > I'm not > saying that people don't denote different things with the same URI, I'm > saying that, by using a URI that someone else controls, you are > accepting their denotation of it.**** > > ** ** > > You're preaching to the choir on that one! I certainly agree with that > architecture, but that is only part of the story. The problem is that there > is inherent ambiguity about the resource that a URI denotes. This is > inescapable. And it means that two different, well-intentioned RDF authors > can reasonably interpret a URI's resource identity differently, and those > differences can cause conflicts to show up when their graphs are merged. > > As a simple example, suppose Owen, a URI owner, mints a URI :apple to > denote an apple. As the URI's owner, he defines the URI's resource identity > using the following RDF statements: > > # Owen's definition of :apple > @prefix : <http://example/owen/> . > :apple a :Apple . > > Arthur, a URI author, then publishes his own RDF statements about Owen's > apple (standard prefix definitions omitted for brevity): > > # Arthur's statements about Owen's apple > @prefix : <http://example/owen/> . > :apple a :GreenApple . > :GreenApple rdfs:subClassOf :Apple . > > Note that Arthur's statements are entirely consistent with Owen's > definition of :apple . > > Now Aster, another URI author, also publishes some RDF statements about > Owen's apple. She also uses Owen's apple definition, but has no knowledge > of Arthur's statements. Aster writes: > > # Aster's statements about Owen's apple > @prefix : <http://example/owen/> . > :apple a :RedApple . > :RedApple rdfs:subClassOf :Apple . > :RedApple owl:disjointWith :GreenApple . > > Note that Aster's statements are also consistent with Owen's definition of > :apple. > > Finally, Connie, an RDF consumer, discovers Arthur and Aster's graphs and > wishes to merge them. Unfortunately, the merge is inconsistent, > > It is tempting to assume that someone did something "wrong" here. For > example, one might claim that Owen's definition was ambiguous, or that > Arthur and Aster should not have made assumptions about the color of Owen's > apple if Owen did not state the color in his definiti >
Received on Sunday, 17 March 2013 04:51:36 UTC